new _(value) → {Object}
Creates a lodash
object which wraps value
to enable implicit method
chain sequences. Methods that operate on and return arrays, collections,
and functions can be chained together. Methods that retrieve a single value
or may return a primitive value will automatically end the chain sequence
and return the unwrapped value. Otherwise, the value must be unwrapped
with _#value
.
Explicit chain sequences, which must be unwrapped with _#value
, may be
enabled using _.chain
.
The execution of chained methods is lazy, that is, it's deferred until
_#value
is implicitly or explicitly called.
Lazy evaluation allows several methods to support shortcut fusion.
Shortcut fusion is an optimization to merge iteratee calls; this avoids
the creation of intermediate arrays and can greatly reduce the number of
iteratee executions. Sections of a chain sequence qualify for shortcut
fusion if the section is applied to an array and iteratees accept only
one argument. The heuristic for whether a section qualifies for shortcut
fusion is subject to change.
Chaining is supported in custom builds as long as the _#value
method is
directly or indirectly included in the build.
In addition to lodash methods, wrappers have Array
and String
methods.
The wrapper Array
methods are:
concat
, join
, pop
, push
, shift
, sort
, splice
, and unshift
The wrapper String
methods are:
replace
and split
The wrapper methods that support shortcut fusion are:
at
, compact
, drop
, dropRight
, dropWhile
, filter
, find
,
findLast
, head
, initial
, last
, map
, reject
, reverse
, slice
,
tail
, take
, takeRight
, takeRightWhile
, takeWhile
, and toArray
The chainable wrapper methods are:
after
, ary
, assign
, assignIn
, assignInWith
, assignWith
, at
,
before
, bind
, bindAll
, bindKey
, castArray
, chain
, chunk
,
commit
, compact
, concat
, conforms
, constant
, countBy
, create
,
curry
, debounce
, defaults
, defaultsDeep
, defer
, delay
,
difference
, differenceBy
, differenceWith
, drop
, dropRight
,
dropRightWhile
, dropWhile
, extend
, extendWith
, fill
, filter
,
flatMap
, flatMapDeep
, flatMapDepth
, flatten
, flattenDeep
,
flattenDepth
, flip
, flow
, flowRight
, fromPairs
, functions
,
functionsIn
, groupBy
, initial
, intersection
, intersectionBy
,
intersectionWith
, invert
, invertBy
, invokeMap
, iteratee
, keyBy
,
keys
, keysIn
, map
, mapKeys
, mapValues
, matches
, matchesProperty
,
memoize
, merge
, mergeWith
, method
, methodOf
, mixin
, negate
,
nthArg
, omit
, omitBy
, once
, orderBy
, over
, overArgs
,
overEvery
, overSome
, partial
, partialRight
, partition
, pick
,
pickBy
, plant
, property
, propertyOf
, pull
, pullAll
, pullAllBy
,
pullAllWith
, pullAt
, push
, range
, rangeRight
, rearg
, reject
,
remove
, rest
, reverse
, sampleSize
, set
, setWith
, shuffle
,
slice
, sort
, sortBy
, splice
, spread
, tail
, take
, takeRight
,
takeRightWhile
, takeWhile
, tap
, throttle
, thru
, toArray
,
toPairs
, toPairsIn
, toPath
, toPlainObject
, transform
, unary
,
union
, unionBy
, unionWith
, uniq
, uniqBy
, uniqWith
, unset
,
unshift
, unzip
, unzipWith
, update
, updateWith
, values
,
valuesIn
, without
, wrap
, xor
, xorBy
, xorWith
, zip
,
zipObject
, zipObjectDeep
, and zipWith
The wrapper methods that are not chainable by default are:
add
, attempt
, camelCase
, capitalize
, ceil
, clamp
, clone
,
cloneDeep
, cloneDeepWith
, cloneWith
, conformsTo
, deburr
,
defaultTo
, divide
, each
, eachRight
, endsWith
, eq
, escape
,
escapeRegExp
, every
, find
, findIndex
, findKey
, findLast
,
findLastIndex
, findLastKey
, first
, floor
, forEach
, forEachRight
,
forIn
, forInRight
, forOwn
, forOwnRight
, get
, gt
, gte
, has
,
hasIn
, head
, identity
, includes
, indexOf
, inRange
, invoke
,
isArguments
, isArray
, isArrayBuffer
, isArrayLike
, isArrayLikeObject
,
isBoolean
, isBuffer
, isDate
, isElement
, isEmpty
, isEqual
,
isEqualWith
, isError
, isFinite
, isFunction
, isInteger
, isLength
,
isMap
, isMatch
, isMatchWith
, isNaN
, isNative
, isNil
, isNull
,
isNumber
, isObject
, isObjectLike
, isPlainObject
, isRegExp
,
isSafeInteger
, isSet
, isString
, isUndefined
, isTypedArray
,
isWeakMap
, isWeakSet
, join
, kebabCase
, last
, lastIndexOf
,
lowerCase
, lowerFirst
, lt
, lte
, max
, maxBy
, mean
, meanBy
,
min
, minBy
, multiply
, noConflict
, noop
, now
, nth
, pad
,
padEnd
, padStart
, parseInt
, pop
, random
, reduce
, reduceRight
,
repeat
, result
, round
, runInContext
, sample
, shift
, size
,
snakeCase
, some
, sortedIndex
, sortedIndexBy
, sortedLastIndex
,
sortedLastIndexBy
, startCase
, startsWith
, stubArray
, stubFalse
,
stubObject
, stubString
, stubTrue
, subtract
, sum
, sumBy
,
template
, times
, toFinite
, toInteger
, toJSON
, toLength
,
toLower
, toNumber
, toSafeInteger
, toString
, toUpper
, trim
,
trimEnd
, trimStart
, truncate
, unescape
, uniqueId
, upperCase
,
upperFirst
, value
, and words
Parameters:
Name | Type | Description |
---|---|---|
value |
* | The value to wrap in a |
Returns:
Object -Returns the new lodash
wrapper instance.
Example
function square(n) {
return n * n;
}
var wrapped = _([1, 2, 3]);
// Returns an unwrapped value.
wrapped.reduce(_.add);
// => 6
// Returns a wrapped value.
var squares = wrapped.map(square);
_.isArray(squares);
// => false
_.isArray(squares.value());
// => true
Members
-
static add
-
Adds two numbers.
- Since:
- 3.4.0
Example
_.add(6, 4); // => 10
-
static assign
-
Assigns own enumerable string keyed properties of source objects to the
destination object. Source objects are applied from left to right.
Subsequent sources overwrite property assignments of previous sources.Note: This method mutates
object
and is loosely based on
Object.assign
.- Since:
- 0.10.0
- See:
-
- _.assignIn
Example
function Foo() { this.a = 1; } function Bar() { this.c = 3; } Foo.prototype.b = 2; Bar.prototype.d = 4; _.assign({ 'a': 0 }, new Foo, new Bar); // => { 'a': 1, 'c': 3 }
-
static assignWith
-
This method is like
_.assign
except that it acceptscustomizer
which is invoked to produce the assigned values. Ifcustomizer
returns
undefined
, assignment is handled by the method instead. Thecustomizer
is invoked with five arguments: (objValue, srcValue, key, object, source).Note: This method mutates
object
.- Since:
- 4.0.0
- See:
-
- _.assignInWith
Example
function customizer(objValue, srcValue) { return _.isUndefined(objValue) ? srcValue : objValue; } var defaults = _.partialRight(_.assignWith, customizer); defaults({ 'a': 1 }, { 'b': 2 }, { 'a': 3 }); // => { 'a': 1, 'b': 2 }
-
static at
-
This method is the wrapper version of
_.at
.- Since:
- 1.0.0
Example
var object = { 'a': [{ 'b': { 'c': 3 } }, 4] }; _(object).at(['a[0].b.c', 'a[1]']).value(); // => [3, 4]
-
static at
-
Creates an array of values corresponding to
paths
ofobject
.- Since:
- 1.0.0
Example
var object = { 'a': [{ 'b': { 'c': 3 } }, 4] }; _.at(object, ['a[0].b.c', 'a[1]']); // => [3, 4]
-
static attempt
-
Attempts to invoke
func
, returning either the result or the caught error
object. Any additional arguments are provided tofunc
when it's invoked.- Since:
- 3.0.0
Example
// Avoid throwing errors for invalid selectors. var elements = _.attempt(function(selector) { return document.querySelectorAll(selector); }, '>_>'); if (_.isError(elements)) { elements = []; }
-
static bind
-
Creates a function that invokes
func
with thethis
binding ofthisArg
andpartials
prepended to the arguments it receives.The
_.bind.placeholder
value, which defaults to_
in monolithic builds,
may be used as a placeholder for partially applied arguments.Note: Unlike native
Function#bind
, this method doesn't set the "length"
property of bound functions.- Since:
- 0.1.0
Example
function greet(greeting, punctuation) { return greeting + ' ' + this.user + punctuation; } var object = { 'user': 'fred' }; var bound = _.bind(greet, object, 'hi'); bound('!'); // => 'hi fred!' // Bound with placeholders. var bound = _.bind(greet, object, _, '!'); bound('hi'); // => 'hi fred!'
-
static bindAll
-
Binds methods of an object to the object itself, overwriting the existing
method.Note: This method doesn't set the "length" property of bound functions.
- Since:
- 0.1.0
Example
var view = { 'label': 'docs', 'click': function() { console.log('clicked ' + this.label); } }; _.bindAll(view, ['click']); jQuery(element).on('click', view.click); // => Logs 'clicked docs' when clicked.
-
static bindKey
-
Creates a function that invokes the method at
object[key]
withpartials
prepended to the arguments it receives.This method differs from
_.bind
by allowing bound functions to reference
methods that may be redefined or don't yet exist. See
Peter Michaux's article
for more details.The
_.bindKey.placeholder
value, which defaults to_
in monolithic
builds, may be used as a placeholder for partially applied arguments.- Since:
- 0.10.0
Example
var object = { 'user': 'fred', 'greet': function(greeting, punctuation) { return greeting + ' ' + this.user + punctuation; } }; var bound = _.bindKey(object, 'greet', 'hi'); bound('!'); // => 'hi fred!' object.greet = function(greeting, punctuation) { return greeting + 'ya ' + this.user + punctuation; }; bound('!'); // => 'hiya fred!' // Bound with placeholders. var bound = _.bindKey(object, 'greet', _, '!'); bound('hi'); // => 'hiya fred!'
-
static camelCase
-
Converts
string
to camel case.- Since:
- 3.0.0
Example
_.camelCase('Foo Bar'); // => 'fooBar' _.camelCase('--foo-bar--'); // => 'fooBar' _.camelCase('__FOO_BAR__'); // => 'fooBar'
-
static ceil
-
Computes
number
rounded up toprecision
.- Since:
- 3.10.0
Example
_.ceil(4.006); // => 5 _.ceil(6.004, 2); // => 6.01 _.ceil(6040, -2); // => 6100
-
static chain
-
Creates a
lodash
wrapper instance with explicit method chain sequences enabled.- Since:
- 0.1.0
Example
var users = [ { 'user': 'barney', 'age': 36 }, { 'user': 'fred', 'age': 40 } ]; // A sequence without explicit chaining. _(users).head(); // => { 'user': 'barney', 'age': 36 } // A sequence with explicit chaining. _(users) .chain() .head() .pick('user') .value(); // => { 'user': 'barney' }
-
static commit
-
Executes the chain sequence and returns the wrapped result.
- Since:
- 3.2.0
Example
var array = [1, 2]; var wrapped = _(array).push(3); console.log(array); // => [1, 2] wrapped = wrapped.commit(); console.log(array); // => [1, 2, 3] wrapped.last(); // => 3 console.log(array); // => [1, 2, 3]
-
static countBy
-
Creates an object composed of keys generated from the results of running
each element ofcollection
thruiteratee
. The corresponding value of
each key is the number of times the key was returned byiteratee
. The
iteratee is invoked with one argument: (value).- Since:
- 0.5.0
Example
_.countBy([6.1, 4.2, 6.3], Math.floor); // => { '4': 1, '6': 2 } // The `_.property` iteratee shorthand. _.countBy(['one', 'two', 'three'], 'length'); // => { '3': 2, '5': 1 }
-
static defaults
-
Assigns own and inherited enumerable string keyed properties of source
objects to the destination object for all destination properties that
resolve toundefined
. Source objects are applied from left to right.
Once a property is set, additional values of the same property are ignored.Note: This method mutates
object
.- Since:
- 0.1.0
- See:
Example
_.defaults({ 'a': 1 }, { 'b': 2 }, { 'a': 3 }); // => { 'a': 1, 'b': 2 }
-
static defaultsDeep
-
This method is like
_.defaults
except that it recursively assigns
default properties.Note: This method mutates
object
.- Since:
- 3.10.0
- See:
Example
_.defaultsDeep({ 'a': { 'b': 2 } }, { 'a': { 'b': 1, 'c': 3 } }); // => { 'a': { 'b': 2, 'c': 3 } }
-
static defer
-
Defers invoking the
func
until the current call stack has cleared. Any
additional arguments are provided tofunc
when it's invoked.- Since:
- 0.1.0
Example
_.defer(function(text) { console.log(text); }, 'deferred'); // => Logs 'deferred' after one millisecond.
-
static delay
-
Invokes
func
afterwait
milliseconds. Any additional arguments are
provided tofunc
when it's invoked.- Since:
- 0.1.0
Example
_.delay(function(text) { console.log(text); }, 1000, 'later'); // => Logs 'later' after one second.
-
static difference
-
Creates an array of
array
values not included in the other given arrays
usingSameValueZero
for equality comparisons. The order and references of result values are
determined by the first array.Note: Unlike
_.pullAll
, this method returns a new array.- Since:
- 0.1.0
- See:
-
- _.without, _.xor
Example
_.difference([2, 1], [2, 3]); // => [1]
-
static differenceBy
-
This method is like
_.difference
except that it acceptsiteratee
which
is invoked for each element ofarray
andvalues
to generate the criterion
by which they're compared. The order and references of result values are
determined by the first array. The iteratee is invoked with one argument:
(value).Note: Unlike
_.pullAllBy
, this method returns a new array.- Since:
- 4.0.0
Example
_.differenceBy([2.1, 1.2], [2.3, 3.4], Math.floor); // => [1.2] // The `_.property` iteratee shorthand. _.differenceBy([{ 'x': 2 }, { 'x': 1 }], [{ 'x': 1 }], 'x'); // => [{ 'x': 2 }]
-
static differenceWith
-
This method is like
_.difference
except that it acceptscomparator
which is invoked to compare elements ofarray
tovalues
. The order and
references of result values are determined by the first array. The comparator
is invoked with two arguments: (arrVal, othVal).Note: Unlike
_.pullAllWith
, this method returns a new array.- Since:
- 4.0.0
Example
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }]; _.differenceWith(objects, [{ 'x': 1, 'y': 2 }], _.isEqual); // => [{ 'x': 2, 'y': 1 }]
-
static divide
-
Divide two numbers.
- Since:
- 4.7.0
Example
_.divide(6, 4); // => 1.5
-
static entries
-
Creates an array of own enumerable string keyed-value pairs for
object
which can be consumed by_.fromPairs
. Ifobject
is a map or set, its
entries are returned.- Since:
- 4.0.0
Example
function Foo() { this.a = 1; this.b = 2; } Foo.prototype.c = 3; _.toPairs(new Foo); // => [['a', 1], ['b', 2]] (iteration order is not guaranteed)
-
static entriesIn
-
Creates an array of own and inherited enumerable string keyed-value pairs
forobject
which can be consumed by_.fromPairs
. Ifobject
is a map
or set, its entries are returned.- Since:
- 4.0.0
Example
function Foo() { this.a = 1; this.b = 2; } Foo.prototype.c = 3; _.toPairsIn(new Foo); // => [['a', 1], ['b', 2], ['c', 3]] (iteration order is not guaranteed)
-
static extend
-
This method is like
_.assign
except that it iterates over own and
inherited source properties.Note: This method mutates
object
.- Since:
- 4.0.0
- See:
Example
function Foo() { this.a = 1; } function Bar() { this.c = 3; } Foo.prototype.b = 2; Bar.prototype.d = 4; _.assignIn({ 'a': 0 }, new Foo, new Bar); // => { 'a': 1, 'b': 2, 'c': 3, 'd': 4 }
-
static extendWith
-
This method is like
_.assignIn
except that it acceptscustomizer
which is invoked to produce the assigned values. Ifcustomizer
returns
undefined
, assignment is handled by the method instead. Thecustomizer
is invoked with five arguments: (objValue, srcValue, key, object, source).Note: This method mutates
object
.- Since:
- 4.0.0
- See:
Example
function customizer(objValue, srcValue) { return _.isUndefined(objValue) ? srcValue : objValue; } var defaults = _.partialRight(_.assignInWith, customizer); defaults({ 'a': 1 }, { 'b': 2 }, { 'a': 3 }); // => { 'a': 1, 'b': 2 }
-
static find
-
Iterates over elements of
collection
, returning the first element
predicate
returns truthy for. The predicate is invoked with three
arguments: (value, index|key, collection).- Since:
- 0.1.0
Example
var users = [ { 'user': 'barney', 'age': 36, 'active': true }, { 'user': 'fred', 'age': 40, 'active': false }, { 'user': 'pebbles', 'age': 1, 'active': true } ]; _.find(users, function(o) { return o.age < 40; }); // => object for 'barney' // The `_.matches` iteratee shorthand. _.find(users, { 'age': 1, 'active': true }); // => object for 'pebbles' // The `_.matchesProperty` iteratee shorthand. _.find(users, ['active', false]); // => object for 'fred' // The `_.property` iteratee shorthand. _.find(users, 'active'); // => object for 'barney'
-
static findLast
-
This method is like
_.find
except that it iterates over elements of
collection
from right to left.- Since:
- 2.0.0
Example
_.findLast([1, 2, 3, 4], function(n) { return n % 2 == 1; }); // => 3
-
static floor
-
Computes
number
rounded down toprecision
.- Since:
- 3.10.0
Example
_.floor(4.006); // => 4 _.floor(0.046, 2); // => 0.04 _.floor(4060, -2); // => 4000
-
static flow
-
Creates a function that returns the result of invoking the given functions
with thethis
binding of the created function, where each successive
invocation is supplied the return value of the previous.- Since:
- 3.0.0
- See:
Example
function square(n) { return n * n; } var addSquare = _.flow([_.add, square]); addSquare(1, 2); // => 9
-
static flowRight
-
This method is like
_.flow
except that it creates a function that
invokes the given functions from right to left.- Since:
- 3.0.0
- See:
Example
function square(n) { return n * n; } var addSquare = _.flowRight([square, _.add]); addSquare(1, 2); // => 9
-
static groupBy
-
Creates an object composed of keys generated from the results of running
each element ofcollection
thruiteratee
. The order of grouped values
is determined by the order they occur incollection
. The corresponding
value of each key is an array of elements responsible for generating the
key. The iteratee is invoked with one argument: (value).- Since:
- 0.1.0
Example
_.groupBy([6.1, 4.2, 6.3], Math.floor); // => { '4': [4.2], '6': [6.1, 6.3] } // The `_.property` iteratee shorthand. _.groupBy(['one', 'two', 'three'], 'length'); // => { '3': ['one', 'two'], '5': ['three'] }
-
static gt
-
Checks if
value
is greater thanother
.- Since:
- 3.9.0
- See:
Example
_.gt(3, 1); // => true _.gt(3, 3); // => false _.gt(1, 3); // => false
-
static gte
-
Checks if
value
is greater than or equal toother
.- Since:
- 3.9.0
- See:
Example
_.gte(3, 1); // => true _.gte(3, 3); // => true _.gte(1, 3); // => false
-
static intersection
-
Creates an array of unique values that are included in all given arrays
usingSameValueZero
for equality comparisons. The order and references of result values are
determined by the first array.- Since:
- 0.1.0
Example
_.intersection([2, 1], [2, 3]); // => [2]
-
static intersectionBy
-
This method is like
_.intersection
except that it acceptsiteratee
which is invoked for each element of eacharrays
to generate the criterion
by which they're compared. The order and references of result values are
determined by the first array. The iteratee is invoked with one argument:
(value).- Since:
- 4.0.0
Example
_.intersectionBy([2.1, 1.2], [2.3, 3.4], Math.floor); // => [2.1] // The `_.property` iteratee shorthand. _.intersectionBy([{ 'x': 1 }], [{ 'x': 2 }, { 'x': 1 }], 'x'); // => [{ 'x': 1 }]
-
static intersectionWith
-
This method is like
_.intersection
except that it acceptscomparator
which is invoked to compare elements ofarrays
. The order and references
of result values are determined by the first array. The comparator is
invoked with two arguments: (arrVal, othVal).- Since:
- 4.0.0
Example
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }]; var others = [{ 'x': 1, 'y': 1 }, { 'x': 1, 'y': 2 }]; _.intersectionWith(objects, others, _.isEqual); // => [{ 'x': 1, 'y': 2 }]
-
static invert
-
Creates an object composed of the inverted keys and values of
object
.
Ifobject
contains duplicate values, subsequent values overwrite
property assignments of previous values.- Since:
- 0.7.0
Example
var object = { 'a': 1, 'b': 2, 'c': 1 }; _.invert(object); // => { '1': 'c', '2': 'b' }
-
static invertBy
-
This method is like
_.invert
except that the inverted object is generated
from the results of running each element ofobject
thruiteratee
. The
corresponding inverted value of each inverted key is an array of keys
responsible for generating the inverted value. The iteratee is invoked
with one argument: (value).- Since:
- 4.1.0
Example
var object = { 'a': 1, 'b': 2, 'c': 1 }; _.invertBy(object); // => { '1': ['a', 'c'], '2': ['b'] } _.invertBy(object, function(value) { return 'group' + value; }); // => { 'group1': ['a', 'c'], 'group2': ['b'] }
-
static invoke
-
Invokes the method at
path
ofobject
.- Since:
- 4.0.0
Example
var object = { 'a': [{ 'b': { 'c': [1, 2, 3, 4] } }] }; _.invoke(object, 'a[0].b.c.slice', 1, 3); // => [2, 3]
-
static invokeMap
-
Invokes the method at
path
of each element incollection
, returning
an array of the results of each invoked method. Any additional arguments
are provided to each invoked method. Ifpath
is a function, it's invoked
for, andthis
bound to, each element incollection
.- Since:
- 4.0.0
Example
_.invokeMap([[5, 1, 7], [3, 2, 1]], 'sort'); // => [[1, 5, 7], [1, 2, 3]] _.invokeMap([123, 456], String.prototype.split, ''); // => [['1', '2', '3'], ['4', '5', '6']]
-
static isArguments
-
Checks if
value
is likely anarguments
object.- Since:
- 0.1.0
Example
_.isArguments(function() { return arguments; }()); // => true _.isArguments([1, 2, 3]); // => false
-
static isArray
-
Checks if
value
is classified as anArray
object.- Since:
- 0.1.0
Example
_.isArray([1, 2, 3]); // => true _.isArray(document.body.children); // => false _.isArray('abc'); // => false _.isArray(_.noop); // => false
-
static isArrayBuffer
-
Checks if
value
is classified as anArrayBuffer
object.- Since:
- 4.3.0
Example
_.isArrayBuffer(new ArrayBuffer(2)); // => true _.isArrayBuffer(new Array(2)); // => false
-
static isBuffer
-
Checks if
value
is a buffer.- Since:
- 4.3.0
Example
_.isBuffer(new Buffer(2)); // => true _.isBuffer(new Uint8Array(2)); // => false
-
static isDate
-
Checks if
value
is classified as aDate
object.- Since:
- 0.1.0
Example
_.isDate(new Date); // => true _.isDate('Mon April 23 2012'); // => false
-
static isMap
-
Checks if
value
is classified as aMap
object.- Since:
- 4.3.0
Example
_.isMap(new Map); // => true _.isMap(new WeakMap); // => false
-
static isRegExp
-
Checks if
value
is classified as aRegExp
object.- Since:
- 0.1.0
Example
_.isRegExp(/abc/); // => true _.isRegExp('/abc/'); // => false
-
static isSet
-
Checks if
value
is classified as aSet
object.- Since:
- 4.3.0
Example
_.isSet(new Set); // => true _.isSet(new WeakSet); // => false
-
static isTypedArray
-
Checks if
value
is classified as a typed array.- Since:
- 3.0.0
Example
_.isTypedArray(new Uint8Array); // => true _.isTypedArray([]); // => false
-
static kebabCase
-
Converts
string
to
kebab case.- Since:
- 3.0.0
Example
_.kebabCase('Foo Bar'); // => 'foo-bar' _.kebabCase('fooBar'); // => 'foo-bar' _.kebabCase('__FOO_BAR__'); // => 'foo-bar'
-
static keyBy
-
Creates an object composed of keys generated from the results of running
each element ofcollection
thruiteratee
. The corresponding value of
each key is the last element responsible for generating the key. The
iteratee is invoked with one argument: (value).- Since:
- 4.0.0
Example
var array = [ { 'dir': 'left', 'code': 97 }, { 'dir': 'right', 'code': 100 } ]; _.keyBy(array, function(o) { return String.fromCharCode(o.code); }); // => { 'a': { 'dir': 'left', 'code': 97 }, 'd': { 'dir': 'right', 'code': 100 } } _.keyBy(array, 'dir'); // => { 'left': { 'dir': 'left', 'code': 97 }, 'right': { 'dir': 'right', 'code': 100 } }
-
static lowerCase
-
Converts
string
, as space separated words, to lower case.- Since:
- 4.0.0
Example
_.lowerCase('--Foo-Bar--'); // => 'foo bar' _.lowerCase('fooBar'); // => 'foo bar' _.lowerCase('__FOO_BAR__'); // => 'foo bar'
-
static lowerFirst
-
Converts the first character of
string
to lower case.- Since:
- 4.0.0
Example
_.lowerFirst('Fred'); // => 'fred' _.lowerFirst('FRED'); // => 'fRED'
-
static lt
-
Checks if
value
is less thanother
.- Since:
- 3.9.0
- See:
Example
_.lt(1, 3); // => true _.lt(3, 3); // => false _.lt(3, 1); // => false
-
static lte
-
Checks if
value
is less than or equal toother
.- Since:
- 3.9.0
- See:
Example
_.lte(1, 3); // => true _.lte(3, 3); // => true _.lte(3, 1); // => false
-
static merge
-
This method is like
_.assign
except that it recursively merges own and
inherited enumerable string keyed properties of source objects into the
destination object. Source properties that resolve toundefined
are
skipped if a destination value exists. Array and plain object properties
are merged recursively. Other objects and value types are overridden by
assignment. Source objects are applied from left to right. Subsequent
sources overwrite property assignments of previous sources.Note: This method mutates
object
.- Since:
- 0.5.0
Example
var object = { 'a': [{ 'b': 2 }, { 'd': 4 }] }; var other = { 'a': [{ 'c': 3 }, { 'e': 5 }] }; _.merge(object, other); // => { 'a': [{ 'b': 2, 'c': 3 }, { 'd': 4, 'e': 5 }] }
-
static mergeWith
-
This method is like
_.merge
except that it acceptscustomizer
which
is invoked to produce the merged values of the destination and source
properties. Ifcustomizer
returnsundefined
, merging is handled by the
method instead. Thecustomizer
is invoked with six arguments:
(objValue, srcValue, key, object, source, stack).Note: This method mutates
object
.- Since:
- 4.0.0
Example
function customizer(objValue, srcValue) { if (_.isArray(objValue)) { return objValue.concat(srcValue); } } var object = { 'a': [1], 'b': [2] }; var other = { 'a': [3], 'b': [4] }; _.mergeWith(object, other, customizer); // => { 'a': [1, 3], 'b': [2, 4] }
-
static method
-
Creates a function that invokes the method at
path
of a given object.
Any additional arguments are provided to the invoked method.- Since:
- 3.7.0
Example
var objects = [ { 'a': { 'b': _.constant(2) } }, { 'a': { 'b': _.constant(1) } } ]; _.map(objects, _.method('a.b')); // => [2, 1] _.map(objects, _.method(['a', 'b'])); // => [2, 1]
-
static methodOf
-
The opposite of
_.method
; this method creates a function that invokes
the method at a given path ofobject
. Any additional arguments are
provided to the invoked method.- Since:
- 3.7.0
Example
var array = _.times(3, _.constant), object = { 'a': array, 'b': array, 'c': array }; _.map(['a[2]', 'c[0]'], _.methodOf(object)); // => [2, 0] _.map([['a', '2'], ['c', '0']], _.methodOf(object)); // => [2, 0]
-
static multiply
-
Multiply two numbers.
- Since:
- 4.7.0
Example
_.multiply(6, 4); // => 24
-
static next
-
Gets the next value on a wrapped object following the
iterator protocol.- Since:
- 4.0.0
Example
var wrapped = _([1, 2]); wrapped.next(); // => { 'done': false, 'value': 1 } wrapped.next(); // => { 'done': false, 'value': 2 } wrapped.next(); // => { 'done': true, 'value': undefined }
-
static now
-
Gets the timestamp of the number of milliseconds that have elapsed since
the Unix epoch (1 January 1970 00:00:00 UTC).- Since:
- 2.4.0
Example
_.defer(function(stamp) { console.log(_.now() - stamp); }, _.now()); // => Logs the number of milliseconds it took for the deferred invocation.
-
static omit
-
The opposite of
_.pick
; this method creates an object composed of the
own and inherited enumerable property paths ofobject
that are not omitted.Note: This method is considerably slower than
_.pick
.- Since:
- 0.1.0
Example
var object = { 'a': 1, 'b': '2', 'c': 3 }; _.omit(object, ['a', 'c']); // => { 'b': '2' }
-
static over
-
Creates a function that invokes
iteratees
with the arguments it receives
and returns their results.- Since:
- 4.0.0
Example
var func = _.over([Math.max, Math.min]); func(1, 2, 3, 4); // => [4, 1]
-
static overArgs
-
Creates a function that invokes
func
with its arguments transformed.- Since:
- 4.0.0
Example
function doubled(n) { return n * 2; } function square(n) { return n * n; } var func = _.overArgs(function(x, y) { return [x, y]; }, [square, doubled]); func(9, 3); // => [81, 6] func(10, 5); // => [100, 10]
-
static overEvery
-
Creates a function that checks if all of the
predicates
return
truthy when invoked with the arguments it receives.- Since:
- 4.0.0
Example
var func = _.overEvery([Boolean, isFinite]); func('1'); // => true func(null); // => false func(NaN); // => false
-
static overSome
-
Creates a function that checks if any of the
predicates
return
truthy when invoked with the arguments it receives.- Since:
- 4.0.0
Example
var func = _.overSome([Boolean, isFinite]); func('1'); // => true func(null); // => true func(NaN); // => false
-
static partial
-
Creates a function that invokes
func
withpartials
prepended to the
arguments it receives. This method is like_.bind
except it does not
alter thethis
binding.The
_.partial.placeholder
value, which defaults to_
in monolithic
builds, may be used as a placeholder for partially applied arguments.Note: This method doesn't set the "length" property of partially
applied functions.- Since:
- 0.2.0
Example
function greet(greeting, name) { return greeting + ' ' + name; } var sayHelloTo = _.partial(greet, 'hello'); sayHelloTo('fred'); // => 'hello fred' // Partially applied with placeholders. var greetFred = _.partial(greet, _, 'fred'); greetFred('hi'); // => 'hi fred'
-
static partialRight
-
This method is like
_.partial
except that partially applied arguments
are appended to the arguments it receives.The
_.partialRight.placeholder
value, which defaults to_
in monolithic
builds, may be used as a placeholder for partially applied arguments.Note: This method doesn't set the "length" property of partially
applied functions.- Since:
- 1.0.0
Example
function greet(greeting, name) { return greeting + ' ' + name; } var greetFred = _.partialRight(greet, 'fred'); greetFred('hi'); // => 'hi fred' // Partially applied with placeholders. var sayHelloTo = _.partialRight(greet, 'hello', _); sayHelloTo('fred'); // => 'hello fred'
-
static partition
-
Creates an array of elements split into two groups, the first of which
contains elementspredicate
returns truthy for, the second of which
contains elementspredicate
returns falsey for. The predicate is
invoked with one argument: (value).- Since:
- 3.0.0
Example
var users = [ { 'user': 'barney', 'age': 36, 'active': false }, { 'user': 'fred', 'age': 40, 'active': true }, { 'user': 'pebbles', 'age': 1, 'active': false } ]; _.partition(users, function(o) { return o.active; }); // => objects for [['fred'], ['barney', 'pebbles']] // The `_.matches` iteratee shorthand. _.partition(users, { 'age': 1, 'active': false }); // => objects for [['pebbles'], ['barney', 'fred']] // The `_.matchesProperty` iteratee shorthand. _.partition(users, ['active', false]); // => objects for [['barney', 'pebbles'], ['fred']] // The `_.property` iteratee shorthand. _.partition(users, 'active'); // => objects for [['fred'], ['barney', 'pebbles']]
-
static pick
-
Creates an object composed of the picked
object
properties.- Since:
- 0.1.0
Example
var object = { 'a': 1, 'b': '2', 'c': 3 }; _.pick(object, ['a', 'c']); // => { 'a': 1, 'c': 3 }
-
static plant
-
Creates a clone of the chain sequence planting
value
as the wrapped value.- Since:
- 3.2.0
Example
function square(n) { return n * n; } var wrapped = _([1, 2]).map(square); var other = wrapped.plant([3, 4]); other.value(); // => [9, 16] wrapped.value(); // => [1, 4]
-
static pull
-
Removes all given values from
array
using
SameValueZero
for equality comparisons.Note: Unlike
_.without
, this method mutatesarray
. Use_.remove
to remove elements from an array by predicate.- Since:
- 2.0.0
Example
var array = ['a', 'b', 'c', 'a', 'b', 'c']; _.pull(array, 'a', 'c'); console.log(array); // => ['b', 'b']
-
static pullAt
-
Removes elements from
array
corresponding toindexes
and returns an
array of removed elements.Note: Unlike
_.at
, this method mutatesarray
.- Since:
- 3.0.0
Example
var array = ['a', 'b', 'c', 'd']; var pulled = _.pullAt(array, [1, 3]); console.log(array); // => ['a', 'c'] console.log(pulled); // => ['b', 'd']
-
static range
-
Creates an array of numbers (positive and/or negative) progressing from
start
up to, but not including,end
. A step of-1
is used if a negative
start
is specified without anend
orstep
. Ifend
is not specified,
it's set tostart
withstart
then set to0
.Note: JavaScript follows the IEEE-754 standard for resolving
floating-point values which can produce unexpected results.- Since:
- 0.1.0
- See:
-
- _.inRange, _.rangeRight
Example
_.range(4); // => [0, 1, 2, 3] _.range(-4); // => [0, -1, -2, -3] _.range(1, 5); // => [1, 2, 3, 4] _.range(0, 20, 5); // => [0, 5, 10, 15] _.range(0, -4, -1); // => [0, -1, -2, -3] _.range(1, 4, 0); // => [1, 1, 1] _.range(0); // => []
-
static rangeRight
-
This method is like
_.range
except that it populates values in
descending order.- Since:
- 4.0.0
- See:
-
- _.inRange, _.range
Example
_.rangeRight(4); // => [3, 2, 1, 0] _.rangeRight(-4); // => [-3, -2, -1, 0] _.rangeRight(1, 5); // => [4, 3, 2, 1] _.rangeRight(0, 20, 5); // => [15, 10, 5, 0] _.rangeRight(0, -4, -1); // => [-3, -2, -1, 0] _.rangeRight(1, 4, 0); // => [1, 1, 1] _.rangeRight(0); // => []
-
static rearg
-
Creates a function that invokes
func
with arguments arranged according
to the specifiedindexes
where the argument value at the first index is
provided as the first argument, the argument value at the second index is
provided as the second argument, and so on.- Since:
- 3.0.0
Example
var rearged = _.rearg(function(a, b, c) { return [a, b, c]; }, [2, 0, 1]); rearged('b', 'c', 'a') // => ['a', 'b', 'c']
-
static reverse
-
This method is the wrapper version of
_.reverse
.Note: This method mutates the wrapped array.
- Since:
- 0.1.0
Example
var array = [1, 2, 3]; _(array).reverse().value() // => [3, 2, 1] console.log(array); // => [3, 2, 1]
-
static round
-
Computes
number
rounded toprecision
.- Since:
- 3.10.0
Example
_.round(4.006); // => 4 _.round(4.006, 2); // => 4.01 _.round(4060, -2); // => 4100
-
static snakeCase
-
Converts
string
to
snake case.- Since:
- 3.0.0
Example
_.snakeCase('Foo Bar'); // => 'foo_bar' _.snakeCase('fooBar'); // => 'foo_bar' _.snakeCase('--FOO-BAR--'); // => 'foo_bar'
-
static sortBy
-
Creates an array of elements, sorted in ascending order by the results of
running each element in a collection thru each iteratee. This method
performs a stable sort, that is, it preserves the original sort order of
equal elements. The iteratees are invoked with one argument: (value).- Since:
- 0.1.0
Example
var users = [ { 'user': 'fred', 'age': 48 }, { 'user': 'barney', 'age': 36 }, { 'user': 'fred', 'age': 40 }, { 'user': 'barney', 'age': 34 } ]; _.sortBy(users, [function(o) { return o.user; }]); // => objects for [['barney', 36], ['barney', 34], ['fred', 48], ['fred', 40]] _.sortBy(users, ['user', 'age']); // => objects for [['barney', 34], ['barney', 36], ['fred', 40], ['fred', 48]]
-
static startCase
-
Converts
string
to
start case.- Since:
- 3.1.0
Example
_.startCase('--foo-bar--'); // => 'Foo Bar' _.startCase('fooBar'); // => 'Foo Bar' _.startCase('__FOO_BAR__'); // => 'FOO BAR'
-
static subtract
-
Subtract two numbers.
- Since:
- 4.0.0
Example
_.subtract(6, 4); // => 2
-
static union
-
Creates an array of unique values, in order, from all given arrays using
SameValueZero
for equality comparisons.- Since:
- 0.1.0
Example
_.union([2], [1, 2]); // => [2, 1]
-
static unionBy
-
This method is like
_.union
except that it acceptsiteratee
which is
invoked for each element of eacharrays
to generate the criterion by
which uniqueness is computed. Result values are chosen from the first
array in which the value occurs. The iteratee is invoked with one argument:
(value).- Since:
- 4.0.0
Example
_.unionBy([2.1], [1.2, 2.3], Math.floor); // => [2.1, 1.2] // The `_.property` iteratee shorthand. _.unionBy([{ 'x': 1 }], [{ 'x': 2 }, { 'x': 1 }], 'x'); // => [{ 'x': 1 }, { 'x': 2 }]
-
static unionWith
-
This method is like
_.union
except that it acceptscomparator
which
is invoked to compare elements ofarrays
. Result values are chosen from
the first array in which the value occurs. The comparator is invoked
with two arguments: (arrVal, othVal).- Since:
- 4.0.0
Example
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }]; var others = [{ 'x': 1, 'y': 1 }, { 'x': 1, 'y': 2 }]; _.unionWith(objects, others, _.isEqual); // => [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }, { 'x': 1, 'y': 1 }]
-
static upperCase
-
Converts
string
, as space separated words, to upper case.- Since:
- 4.0.0
Example
_.upperCase('--foo-bar'); // => 'FOO BAR' _.upperCase('fooBar'); // => 'FOO BAR' _.upperCase('__foo_bar__'); // => 'FOO BAR'
-
static upperFirst
-
Converts the first character of
string
to upper case.- Since:
- 4.0.0
Example
_.upperFirst('fred'); // => 'Fred' _.upperFirst('FRED'); // => 'FRED'
-
static without
-
Creates an array excluding all given values using
SameValueZero
for equality comparisons.Note: Unlike
_.pull
, this method returns a new array.- Since:
- 0.1.0
- See:
-
- _.difference, _.xor
Example
_.without([2, 1, 2, 3], 1, 2); // => [3]
-
static xor
-
Creates an array of unique values that is the
symmetric difference
of the given arrays. The order of result values is determined by the order
they occur in the arrays.- Since:
- 2.4.0
- See:
-
- _.difference, _.without
Example
_.xor([2, 1], [2, 3]); // => [1, 3]
-
static xorBy
-
This method is like
_.xor
except that it acceptsiteratee
which is
invoked for each element of eacharrays
to generate the criterion by
which by which they're compared. The order of result values is determined
by the order they occur in the arrays. The iteratee is invoked with one
argument: (value).- Since:
- 4.0.0
Example
_.xorBy([2.1, 1.2], [2.3, 3.4], Math.floor); // => [1.2, 3.4] // The `_.property` iteratee shorthand. _.xorBy([{ 'x': 1 }], [{ 'x': 2 }, { 'x': 1 }], 'x'); // => [{ 'x': 2 }]
-
static xorWith
-
This method is like
_.xor
except that it acceptscomparator
which is
invoked to compare elements ofarrays
. The order of result values is
determined by the order they occur in the arrays. The comparator is invoked
with two arguments: (arrVal, othVal).- Since:
- 4.0.0
Example
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }]; var others = [{ 'x': 1, 'y': 1 }, { 'x': 1, 'y': 2 }]; _.xorWith(objects, others, _.isEqual); // => [{ 'x': 2, 'y': 1 }, { 'x': 1, 'y': 1 }]
-
static zip
-
Creates an array of grouped elements, the first of which contains the
first elements of the given arrays, the second of which contains the
second elements of the given arrays, and so on.- Since:
- 0.1.0
Example
_.zip(['a', 'b'], [1, 2], [true, false]); // => [['a', 1, true], ['b', 2, false]]
-
static zipWith
-
This method is like
_.zip
except that it acceptsiteratee
to specify
how grouped values should be combined. The iteratee is invoked with the
elements of each group: (...group).- Since:
- 3.8.0
Example
_.zipWith([1, 2], [10, 20], [100, 200], function(a, b, c) { return a + b + c; }); // => [111, 222]
-
value
-
Executes the chain sequence to resolve the unwrapped value.
- Since:
- 0.1.0
Example
_([1, 2, 3]).value(); // => [1, 2, 3]
Methods
-
static after(n, func) → {function}
-
The opposite of
_.before
; this method creates a function that invokes
func
once it's calledn
or more times.Parameters:
Name Type Description n
number The number of calls before
func
is invoked.func
function The function to restrict.
Returns:
function -Returns the new restricted function.
- Since:
- 0.1.0
Example
var saves = ['profile', 'settings']; var done = _.after(saves.length, function() { console.log('done saving!'); }); _.forEach(saves, function(type) { asyncSave({ 'type': type, 'complete': done }); }); // => Logs 'done saving!' after the two async saves have completed.
-
static ary(func, nopt) → {function}
-
Creates a function that invokes
func
, with up ton
arguments,
ignoring any additional arguments.Parameters:
Name Type Attributes Default Description func
function The function to cap arguments for.
n
number <optional>
func.length The arity cap.
Returns:
function -Returns the new capped function.
- Since:
- 3.0.0
Example
_.map(['6', '8', '10'], _.ary(parseInt, 1)); // => [6, 8, 10]
-
static before(n, func) → {function}
-
Creates a function that invokes
func
, with thethis
binding and arguments
of the created function, while it's called less thann
times. Subsequent
calls to the created function return the result of the lastfunc
invocation.Parameters:
Name Type Description n
number The number of calls at which
func
is no longer invoked.func
function The function to restrict.
Returns:
function -Returns the new restricted function.
- Since:
- 3.0.0
Example
jQuery(element).on('click', _.before(5, addContactToList)); // => Allows adding up to 4 contacts to the list.
-
static capitalize(stringopt) → {string}
-
Converts the first character of
string
to upper case and the remaining
to lower case.Parameters:
Name Type Attributes Default Description string
string <optional>
'' The string to capitalize.
Returns:
string -Returns the capitalized string.
- Since:
- 3.0.0
Example
_.capitalize('FRED'); // => 'Fred'
-
static castArray(value) → {Array}
-
Casts
value
as an array if it's not one.Parameters:
Name Type Description value
* The value to inspect.
Returns:
Array -Returns the cast array.
- Since:
- 4.4.0
Example
_.castArray(1); // => [1] _.castArray({ 'a': 1 }); // => [{ 'a': 1 }] _.castArray('abc'); // => ['abc'] _.castArray(null); // => [null] _.castArray(undefined); // => [undefined] _.castArray(); // => [] var array = [1, 2, 3]; console.log(_.castArray(array) === array); // => true
-
static chain(value) → {Object}
-
Creates a
lodash
wrapper instance that wrapsvalue
with explicit method
chain sequences enabled. The result of such sequences must be unwrapped
with_#value
.Parameters:
Name Type Description value
* The value to wrap.
Returns:
Object -Returns the new
lodash
wrapper instance.- Since:
- 1.3.0
Example
var users = [ { 'user': 'barney', 'age': 36 }, { 'user': 'fred', 'age': 40 }, { 'user': 'pebbles', 'age': 1 } ]; var youngest = _ .chain(users) .sortBy('age') .map(function(o) { return o.user + ' is ' + o.age; }) .head() .value(); // => 'pebbles is 1'
-
static chunk(array, sizeopt) → {Array}
-
Creates an array of elements split into groups the length of
size
.
Ifarray
can't be split evenly, the final chunk will be the remaining
elements.Parameters:
Name Type Attributes Default Description array
Array The array to process.
size
number <optional>
1 The length of each chunk
Returns:
Array -Returns the new array of chunks.
- Since:
- 3.0.0
Example
_.chunk(['a', 'b', 'c', 'd'], 2); // => [['a', 'b'], ['c', 'd']] _.chunk(['a', 'b', 'c', 'd'], 3); // => [['a', 'b', 'c'], ['d']]
-
static clamp(number, loweropt, upper) → {number}
-
Clamps
number
within the inclusivelower
andupper
bounds.Parameters:
Name Type Attributes Description number
number The number to clamp.
lower
number <optional>
The lower bound.
upper
number The upper bound.
Returns:
number -Returns the clamped number.
- Since:
- 4.0.0
Example
_.clamp(-10, -5, 5); // => -5 _.clamp(10, -5, 5); // => 5
-
static clone(value) → {*}
-
Creates a shallow clone of
value
.Note: This method is loosely based on the
structured clone algorithm
and supports cloning arrays, array buffers, booleans, date objects, maps,
numbers,Object
objects, regexes, sets, strings, symbols, and typed
arrays. The own enumerable properties ofarguments
objects are cloned
as plain objects. An empty object is returned for uncloneable values such
as error objects, functions, DOM nodes, and WeakMaps.Parameters:
Name Type Description value
* The value to clone.
Returns:
* -Returns the cloned value.
- Since:
- 0.1.0
- See:
Example
var objects = [{ 'a': 1 }, { 'b': 2 }]; var shallow = _.clone(objects); console.log(shallow[0] === objects[0]); // => true
-
static cloneDeep(value) → {*}
-
This method is like
_.clone
except that it recursively clonesvalue
.Parameters:
Name Type Description value
* The value to recursively clone.
Returns:
* -Returns the deep cloned value.
- Since:
- 1.0.0
- See:
Example
var objects = [{ 'a': 1 }, { 'b': 2 }]; var deep = _.cloneDeep(objects); console.log(deep[0] === objects[0]); // => false
-
static cloneDeepWith(value, customizeropt) → {*}
-
This method is like
_.cloneWith
except that it recursively clonesvalue
.Parameters:
Name Type Attributes Description value
* The value to recursively clone.
customizer
function <optional>
The function to customize cloning.
Returns:
* -Returns the deep cloned value.
- Since:
- 4.0.0
- See:
Example
function customizer(value) { if (_.isElement(value)) { return value.cloneNode(true); } } var el = _.cloneDeepWith(document.body, customizer); console.log(el === document.body); // => false console.log(el.nodeName); // => 'BODY' console.log(el.childNodes.length); // => 20
-
static cloneWith(value, customizeropt) → {*}
-
This method is like
_.clone
except that it acceptscustomizer
which
is invoked to produce the cloned value. Ifcustomizer
returnsundefined
,
cloning is handled by the method instead. Thecustomizer
is invoked with
up to four arguments; (value [, index|key, object, stack]).Parameters:
Name Type Attributes Description value
* The value to clone.
customizer
function <optional>
The function to customize cloning.
Returns:
* -Returns the cloned value.
- Since:
- 4.0.0
- See:
Example
function customizer(value) { if (_.isElement(value)) { return value.cloneNode(false); } } var el = _.cloneWith(document.body, customizer); console.log(el === document.body); // => false console.log(el.nodeName); // => 'BODY' console.log(el.childNodes.length); // => 0
-
static compact(array) → {Array}
-
Creates an array with all falsey values removed. The values
false
,null
,
0
,""
,undefined
, andNaN
are falsey.Parameters:
Name Type Description array
Array The array to compact.
Returns:
Array -Returns the new array of filtered values.
- Since:
- 0.1.0
Example
_.compact([0, 1, false, 2, '', 3]); // => [1, 2, 3]
-
static concat(array, …valuesopt) → {Array}
-
Creates a new array concatenating
array
with any additional arrays
and/or values.Parameters:
Name Type Attributes Description array
Array The array to concatenate.
values
* <optional>
<repeatable>
The values to concatenate.
Returns:
Array -Returns the new concatenated array.
- Since:
- 4.0.0
Example
var array = [1]; var other = _.concat(array, 2, [3], [[4]]); console.log(other); // => [1, 2, 3, [4]] console.log(array); // => [1]
-
static cond(pairs) → {function}
-
Creates a function that iterates over
pairs
and invokes the corresponding
function of the first predicate to return truthy. The predicate-function
pairs are invoked with thethis
binding and arguments of the created
function.Parameters:
Name Type Description pairs
Array The predicate-function pairs.
Returns:
function -Returns the new composite function.
- Since:
- 4.0.0
Example
var func = _.cond([ [_.matches({ 'a': 1 }), _.constant('matches A')], [_.conforms({ 'b': _.isNumber }), _.constant('matches B')], [_.stubTrue, _.constant('no match')] ]); func({ 'a': 1, 'b': 2 }); // => 'matches A' func({ 'a': 0, 'b': 1 }); // => 'matches B' func({ 'a': '1', 'b': '2' }); // => 'no match'
-
static conforms(source) → {function}
-
Creates a function that invokes the predicate properties of
source
with
the corresponding property values of a given object, returningtrue
if
all predicates return truthy, elsefalse
.Note: The created function is equivalent to
_.conformsTo
with
source
partially applied.Parameters:
Name Type Description source
Object The object of property predicates to conform to.
Returns:
function -Returns the new spec function.
- Since:
- 4.0.0
Example
var objects = [ { 'a': 2, 'b': 1 }, { 'a': 1, 'b': 2 } ]; _.filter(objects, _.conforms({ 'b': function(n) { return n > 1; } })); // => [{ 'a': 1, 'b': 2 }]
-
static conformsTo(object, source) → {boolean}
-
Checks if
object
conforms tosource
by invoking the predicate
properties ofsource
with the corresponding property values ofobject
.Note: This method is equivalent to
_.conforms
whensource
is
partially applied.Parameters:
Name Type Description object
Object The object to inspect.
source
Object The object of property predicates to conform to.
Returns:
boolean -Returns
true
ifobject
conforms, elsefalse
.- Since:
- 4.14.0
Example
var object = { 'a': 1, 'b': 2 }; _.conformsTo(object, { 'b': function(n) { return n > 1; } }); // => true _.conformsTo(object, { 'b': function(n) { return n > 2; } }); // => false
-
static constant(value) → {function}
-
Creates a function that returns
value
.Parameters:
Name Type Description value
* The value to return from the new function.
Returns:
function -Returns the new constant function.
- Since:
- 2.4.0
Example
var objects = _.times(2, _.constant({ 'a': 1 })); console.log(objects); // => [{ 'a': 1 }, { 'a': 1 }] console.log(objects[0] === objects[1]); // => true
-
static create(prototype, propertiesopt) → {Object}
-
Creates an object that inherits from the
prototype
object. If a
properties
object is given, its own enumerable string keyed properties
are assigned to the created object.Parameters:
Name Type Attributes Description prototype
Object The object to inherit from.
properties
Object <optional>
The properties to assign to the object.
Returns:
Object -Returns the new object.
- Since:
- 2.3.0
Example
function Shape() { this.x = 0; this.y = 0; } function Circle() { Shape.call(this); } Circle.prototype = _.create(Shape.prototype, { 'constructor': Circle }); var circle = new Circle; circle instanceof Circle; // => true circle instanceof Shape; // => true
-
static curry(func, arityopt) → {function}
-
Creates a function that accepts arguments of
func
and either invokes
func
returning its result, if at leastarity
number of arguments have
been provided, or returns a function that accepts the remainingfunc
arguments, and so on. The arity offunc
may be specified iffunc.length
is not sufficient.The
_.curry.placeholder
value, which defaults to_
in monolithic builds,
may be used as a placeholder for provided arguments.Note: This method doesn't set the "length" property of curried functions.
Parameters:
Name Type Attributes Default Description func
function The function to curry.
arity
number <optional>
func.length The arity of
func
.Returns:
function -Returns the new curried function.
- Since:
- 2.0.0
Example
var abc = function(a, b, c) { return [a, b, c]; }; var curried = _.curry(abc); curried(1)(2)(3); // => [1, 2, 3] curried(1, 2)(3); // => [1, 2, 3] curried(1, 2, 3); // => [1, 2, 3] // Curried with placeholders. curried(1)(_, 3)(2); // => [1, 2, 3]
-
static curryRight(func, arityopt) → {function}
-
This method is like
_.curry
except that arguments are applied tofunc
in the manner of_.partialRight
instead of_.partial
.The
_.curryRight.placeholder
value, which defaults to_
in monolithic
builds, may be used as a placeholder for provided arguments.Note: This method doesn't set the "length" property of curried functions.
Parameters:
Name Type Attributes Default Description func
function The function to curry.
arity
number <optional>
func.length The arity of
func
.Returns:
function -Returns the new curried function.
- Since:
- 3.0.0
Example
var abc = function(a, b, c) { return [a, b, c]; }; var curried = _.curryRight(abc); curried(3)(2)(1); // => [1, 2, 3] curried(2, 3)(1); // => [1, 2, 3] curried(1, 2, 3); // => [1, 2, 3] // Curried with placeholders. curried(3)(1, _)(2); // => [1, 2, 3]
-
static debounce(func, waitopt, optionsopt) → {function}
-
Creates a debounced function that delays invoking
func
until afterwait
milliseconds have elapsed since the last time the debounced function was
invoked. The debounced function comes with acancel
method to cancel
delayedfunc
invocations and aflush
method to immediately invoke them.
Provideoptions
to indicate whetherfunc
should be invoked on the
leading and/or trailing edge of thewait
timeout. Thefunc
is invoked
with the last arguments provided to the debounced function. Subsequent
calls to the debounced function return the result of the lastfunc
invocation.Note: If
leading
andtrailing
options aretrue
,func
is
invoked on the trailing edge of the timeout only if the debounced function
is invoked more than once during thewait
timeout.If
wait
is0
andleading
isfalse
,func
invocation is deferred
until to the next tick, similar tosetTimeout
with a timeout of0
.See David Corbacho's article
for details over the differences between_.debounce
and_.throttle
.Parameters:
Name Type Attributes Default Description func
function The function to debounce.
wait
number <optional>
0 The number of milliseconds to delay.
options
Object <optional>
{} The options object.
Properties
Name Type Attributes Default Description leading
boolean <optional>
false Specify invoking on the leading edge of the timeout.
maxWait
number <optional>
The maximum time
func
is allowed to be delayed before it's invoked.trailing
boolean <optional>
true Specify invoking on the trailing edge of the timeout.
Returns:
function -Returns the new debounced function.
- Since:
- 0.1.0
Example
// Avoid costly calculations while the window size is in flux. jQuery(window).on('resize', _.debounce(calculateLayout, 150)); // Invoke `sendMail` when clicked, debouncing subsequent calls. jQuery(element).on('click', _.debounce(sendMail, 300, { 'leading': true, 'trailing': false })); // Ensure `batchLog` is invoked once after 1 second of debounced calls. var debounced = _.debounce(batchLog, 250, { 'maxWait': 1000 }); var source = new EventSource('/stream'); jQuery(source).on('message', debounced); // Cancel the trailing debounced invocation. jQuery(window).on('popstate', debounced.cancel);
-
static deburr(stringopt) → {string}
-
Deburrs
string
by converting
Latin-1 Supplement
and Latin Extended-A
letters to basic Latin letters and removing
combining diacritical marks.Parameters:
Name Type Attributes Default Description string
string <optional>
'' The string to deburr.
Returns:
string -Returns the deburred string.
- Since:
- 3.0.0
Example
_.deburr('déjà vu'); // => 'deja vu'
-
static defaultTo(value, defaultValue) → {*}
-
Checks
value
to determine whether a default value should be returned in
its place. ThedefaultValue
is returned ifvalue
isNaN
,null
,
orundefined
.Parameters:
Name Type Description value
* The value to check.
defaultValue
* The default value.
Returns:
* -Returns the resolved value.
- Since:
- 4.14.0
Example
_.defaultTo(1, 10); // => 1 _.defaultTo(undefined, 10); // => 10
-
static drop(array, nopt) → {Array}
-
Creates a slice of
array
withn
elements dropped from the beginning.Parameters:
Name Type Attributes Default Description array
Array The array to query.
n
number <optional>
1 The number of elements to drop.
Returns:
Array -Returns the slice of
array
.- Since:
- 0.5.0
Example
_.drop([1, 2, 3]); // => [2, 3] _.drop([1, 2, 3], 2); // => [3] _.drop([1, 2, 3], 5); // => [] _.drop([1, 2, 3], 0); // => [1, 2, 3]
-
static dropRight(array, nopt) → {Array}
-
Creates a slice of
array
withn
elements dropped from the end.Parameters:
Name Type Attributes Default Description array
Array The array to query.
n
number <optional>
1 The number of elements to drop.
Returns:
Array -Returns the slice of
array
.- Since:
- 3.0.0
Example
_.dropRight([1, 2, 3]); // => [1, 2] _.dropRight([1, 2, 3], 2); // => [1] _.dropRight([1, 2, 3], 5); // => [] _.dropRight([1, 2, 3], 0); // => [1, 2, 3]
-
static dropRightWhile(array, predicateopt) → {Array}
-
Creates a slice of
array
excluding elements dropped from the end.
Elements are dropped untilpredicate
returns falsey. The predicate is
invoked with three arguments: (value, index, array).Parameters:
Name Type Attributes Default Description array
Array The array to query.
predicate
function <optional>
_.identity The function invoked per iteration.
Returns:
Array -Returns the slice of
array
.- Since:
- 3.0.0
Example
var users = [ { 'user': 'barney', 'active': true }, { 'user': 'fred', 'active': false }, { 'user': 'pebbles', 'active': false } ]; _.dropRightWhile(users, function(o) { return !o.active; }); // => objects for ['barney'] // The `_.matches` iteratee shorthand. _.dropRightWhile(users, { 'user': 'pebbles', 'active': false }); // => objects for ['barney', 'fred'] // The `_.matchesProperty` iteratee shorthand. _.dropRightWhile(users, ['active', false]); // => objects for ['barney'] // The `_.property` iteratee shorthand. _.dropRightWhile(users, 'active'); // => objects for ['barney', 'fred', 'pebbles']
-
static dropWhile(array, predicateopt) → {Array}
-
Creates a slice of
array
excluding elements dropped from the beginning.
Elements are dropped untilpredicate
returns falsey. The predicate is
invoked with three arguments: (value, index, array).Parameters:
Name Type Attributes Default Description array
Array The array to query.
predicate
function <optional>
_.identity The function invoked per iteration.
Returns:
Array -Returns the slice of
array
.- Since:
- 3.0.0
Example
var users = [ { 'user': 'barney', 'active': false }, { 'user': 'fred', 'active': false }, { 'user': 'pebbles', 'active': true } ]; _.dropWhile(users, function(o) { return !o.active; }); // => objects for ['pebbles'] // The `_.matches` iteratee shorthand. _.dropWhile(users, { 'user': 'barney', 'active': false }); // => objects for ['fred', 'pebbles'] // The `_.matchesProperty` iteratee shorthand. _.dropWhile(users, ['active', false]); // => objects for ['pebbles'] // The `_.property` iteratee shorthand. _.dropWhile(users, 'active'); // => objects for ['barney', 'fred', 'pebbles']
-
static each(collection, iterateeopt) → {Array|Object}
-
Iterates over elements of
collection
and invokesiteratee
for each element.
The iteratee is invoked with three arguments: (value, index|key, collection).
Iteratee functions may exit iteration early by explicitly returningfalse
.Note: As with other "Collections" methods, objects with a "length"
property are iterated like arrays. To avoid this behavior use_.forIn
or_.forOwn
for object iteration.Parameters:
Name Type Attributes Default Description collection
Array | Object The collection to iterate over.
iteratee
function <optional>
_.identity The function invoked per iteration.
Returns:
Array | Object -Returns
collection
.- Since:
- 0.1.0
- See:
-
- _.forEachRight
Example
_.forEach([1, 2], function(value) { console.log(value); }); // => Logs `1` then `2`. _.forEach({ 'a': 1, 'b': 2 }, function(value, key) { console.log(key); }); // => Logs 'a' then 'b' (iteration order is not guaranteed).
-
static eachRight(collection, iterateeopt) → {Array|Object}
-
This method is like
_.forEach
except that it iterates over elements of
collection
from right to left.Parameters:
Name Type Attributes Default Description collection
Array | Object The collection to iterate over.
iteratee
function <optional>
_.identity The function invoked per iteration.
Returns:
Array | Object -Returns
collection
.- Since:
- 2.0.0
- See:
-
- _.forEach
Example
_.forEachRight([1, 2], function(value) { console.log(value); }); // => Logs `2` then `1`.
-
static endsWith(stringopt, targetopt, positionopt) → {boolean}
-
Checks if
string
ends with the given target string.Parameters:
Name Type Attributes Default Description string
string <optional>
'' The string to inspect.
target
string <optional>
The string to search for.
position
number <optional>
string.length The position to search up to.
Returns:
boolean -Returns
true
ifstring
ends withtarget
,
elsefalse
.- Since:
- 3.0.0
Example
_.endsWith('abc', 'c'); // => true _.endsWith('abc', 'b'); // => false _.endsWith('abc', 'b', 2); // => true
-
static eq(value, other) → {boolean}
-
Performs a
SameValueZero
comparison between two values to determine if they are equivalent.Parameters:
Name Type Description value
* The value to compare.
other
* The other value to compare.
Returns:
boolean -Returns
true
if the values are equivalent, elsefalse
.- Since:
- 4.0.0
Example
var object = { 'a': 1 }; var other = { 'a': 1 }; _.eq(object, object); // => true _.eq(object, other); // => false _.eq('a', 'a'); // => true _.eq('a', Object('a')); // => false _.eq(NaN, NaN); // => true
-
static escape(stringopt) → {string}
-
Converts the characters "&", "<", ">", '"', and "'" in
string
to their
corresponding HTML entities.Note: No other characters are escaped. To escape additional
characters use a third-party library like he.Though the ">" character is escaped for symmetry, characters like
">" and "/" don't need escaping in HTML and have no special meaning
unless they're part of a tag or unquoted attribute value. See
Mathias Bynens's article
(under "semi-related fun fact") for more details.When working with HTML you should always
quote attribute values to reduce
XSS vectors.Parameters:
Name Type Attributes Default Description string
string <optional>
'' The string to escape.
Returns:
string -Returns the escaped string.
- Since:
- 0.1.0
Example
_.escape('fred, barney, & pebbles'); // => 'fred, barney, & pebbles'
-
static escapeRegExp(stringopt) → {string}
-
Escapes the
RegExp
special characters "^", "$", "", ".", "*", "+",
"?", "(", ")", "[", "]", "{", "}", and "|" instring
.Parameters:
Name Type Attributes Default Description string
string <optional>
'' The string to escape.
Returns:
string -Returns the escaped string.
- Since:
- 3.0.0
Example
_.escapeRegExp('[lodash](https://lodash.com/)'); // => '\[lodash\]\(https://lodash\.com/\)'
-
static every(collection, predicateopt) → {boolean}
-
Checks if
predicate
returns truthy for all elements ofcollection
.
Iteration is stopped oncepredicate
returns falsey. The predicate is
invoked with three arguments: (value, index|key, collection).Note: This method returns
true
for
empty collections because
everything is true of
elements of empty collections.Parameters:
Name Type Attributes Default Description collection
Array | Object The collection to iterate over.
predicate
function <optional>
_.identity The function invoked per iteration.
Returns:
boolean -Returns
true
if all elements pass the predicate check,
elsefalse
.- Since:
- 0.1.0
Example
_.every([true, 1, null, 'yes'], Boolean); // => false var users = [ { 'user': 'barney', 'age': 36, 'active': false }, { 'user': 'fred', 'age': 40, 'active': false } ]; // The `_.matches` iteratee shorthand. _.every(users, { 'user': 'barney', 'active': false }); // => false // The `_.matchesProperty` iteratee shorthand. _.every(users, ['active', false]); // => true // The `_.property` iteratee shorthand. _.every(users, 'active'); // => false
-
static fill(array, value, startopt, endopt) → {Array}
-
Fills elements of
array
withvalue
fromstart
up to, but not
including,end
.Note: This method mutates
array
.Parameters:
Name Type Attributes Default Description array
Array The array to fill.
value
* The value to fill
array
with.start
number <optional>
0 The start position.
end
number <optional>
array.length The end position.
Returns:
Array -Returns
array
.- Since:
- 3.2.0
Example
var array = [1, 2, 3]; _.fill(array, 'a'); console.log(array); // => ['a', 'a', 'a'] _.fill(Array(3), 2); // => [2, 2, 2] _.fill([4, 6, 8, 10], '*', 1, 3); // => [4, '*', '*', 10]
-
static filter(collection, predicateopt) → {Array}
-
Iterates over elements of
collection
, returning an array of all elements
predicate
returns truthy for. The predicate is invoked with three
arguments: (value, index|key, collection).Note: Unlike
_.remove
, this method returns a new array.Parameters:
Name Type Attributes Default Description collection
Array | Object The collection to iterate over.
predicate
function <optional>
_.identity The function invoked per iteration.
Returns:
Array -Returns the new filtered array.
- Since:
- 0.1.0
- See:
Example
var users = [ { 'user': 'barney', 'age': 36, 'active': true }, { 'user': 'fred', 'age': 40, 'active': false } ]; _.filter(users, function(o) { return !o.active; }); // => objects for ['fred'] // The `_.matches` iteratee shorthand. _.filter(users, { 'age': 36, 'active': true }); // => objects for ['barney'] // The `_.matchesProperty` iteratee shorthand. _.filter(users, ['active', false]); // => objects for ['fred'] // The `_.property` iteratee shorthand. _.filter(users, 'active'); // => objects for ['barney']
-
static findIndex(array, predicateopt, fromIndexopt) → {number}
-
This method is like
_.find
except that it returns the index of the first
elementpredicate
returns truthy for instead of the element itself.Parameters:
Name Type Attributes Default Description array
Array The array to inspect.
predicate
function <optional>
_.identity The function invoked per iteration.
fromIndex
number <optional>
0 The index to search from.
Returns:
number -Returns the index of the found element, else
-1
.- Since:
- 1.1.0
Example
var users = [ { 'user': 'barney', 'active': false }, { 'user': 'fred', 'active': false }, { 'user': 'pebbles', 'active': true } ]; _.findIndex(users, function(o) { return o.user == 'barney'; }); // => 0 // The `_.matches` iteratee shorthand. _.findIndex(users, { 'user': 'fred', 'active': false }); // => 1 // The `_.matchesProperty` iteratee shorthand. _.findIndex(users, ['active', false]); // => 0 // The `_.property` iteratee shorthand. _.findIndex(users, 'active'); // => 2
-
static findKey(object, predicateopt) → {string|undefined}
-
This method is like
_.find
except that it returns the key of the first
elementpredicate
returns truthy for instead of the element itself.Parameters:
Name Type Attributes Default Description object
Object The object to inspect.
predicate
function <optional>
_.identity The function invoked per iteration.
Returns:
string | undefined -Returns the key of the matched element,
elseundefined
.- Since:
- 1.1.0
Example
var users = { 'barney': { 'age': 36, 'active': true }, 'fred': { 'age': 40, 'active': false }, 'pebbles': { 'age': 1, 'active': true } }; _.findKey(users, function(o) { return o.age < 40; }); // => 'barney' (iteration order is not guaranteed) // The `_.matches` iteratee shorthand. _.findKey(users, { 'age': 1, 'active': true }); // => 'pebbles' // The `_.matchesProperty` iteratee shorthand. _.findKey(users, ['active', false]); // => 'fred' // The `_.property` iteratee shorthand. _.findKey(users, 'active'); // => 'barney'
-
static findLastIndex(array, predicateopt, fromIndexopt) → {number}
-
This method is like
_.findIndex
except that it iterates over elements
ofcollection
from right to left.Parameters:
Name Type Attributes Default Description array
Array The array to inspect.
predicate
function <optional>
_.identity The function invoked per iteration.
fromIndex
number <optional>
array.length-1 The index to search from.
Returns:
number -Returns the index of the found element, else
-1
.- Since:
- 2.0.0
Example
var users = [ { 'user': 'barney', 'active': true }, { 'user': 'fred', 'active': false }, { 'user': 'pebbles', 'active': false } ]; _.findLastIndex(users, function(o) { return o.user == 'pebbles'; }); // => 2 // The `_.matches` iteratee shorthand. _.findLastIndex(users, { 'user': 'barney', 'active': true }); // => 0 // The `_.matchesProperty` iteratee shorthand. _.findLastIndex(users, ['active', false]); // => 2 // The `_.property` iteratee shorthand. _.findLastIndex(users, 'active'); // => 0
-
static findLastKey(object, predicateopt) → {string|undefined}
-
This method is like
_.findKey
except that it iterates over elements of
a collection in the opposite order.Parameters:
Name Type Attributes Default Description object
Object The object to inspect.
predicate
function <optional>
_.identity The function invoked per iteration.
Returns:
string | undefined -Returns the key of the matched element,
elseundefined
.- Since:
- 2.0.0
Example
var users = { 'barney': { 'age': 36, 'active': true }, 'fred': { 'age': 40, 'active': false }, 'pebbles': { 'age': 1, 'active': true } }; _.findLastKey(users, function(o) { return o.age < 40; }); // => returns 'pebbles' assuming `_.findKey` returns 'barney' // The `_.matches` iteratee shorthand. _.findLastKey(users, { 'age': 36, 'active': true }); // => 'barney' // The `_.matchesProperty` iteratee shorthand. _.findLastKey(users, ['active', false]); // => 'fred' // The `_.property` iteratee shorthand. _.findLastKey(users, 'active'); // => 'pebbles'
-
static first(array) → {*}
-
Gets the first element of
array
.Parameters:
Name Type Description array
Array The array to query.
Returns:
* -Returns the first element of
array
.- Since:
- 0.1.0
Example
_.head([1, 2, 3]); // => 1 _.head([]); // => undefined
-
static flatMap(collection, iterateeopt) → {Array}
-
Creates a flattened array of values by running each element in
collection
thruiteratee
and flattening the mapped results. The iteratee is invoked
with three arguments: (value, index|key, collection).Parameters:
Name Type Attributes Default Description collection
Array | Object The collection to iterate over.
iteratee
function <optional>
_.identity The function invoked per iteration.
Returns:
Array -Returns the new flattened array.
- Since:
- 4.0.0
Example
function duplicate(n) { return [n, n]; } _.flatMap([1, 2], duplicate); // => [1, 1, 2, 2]
-
static flatMapDeep(collection, iterateeopt) → {Array}
-
This method is like
_.flatMap
except that it recursively flattens the
mapped results.Parameters:
Name Type Attributes Default Description collection
Array | Object The collection to iterate over.
iteratee
function <optional>
_.identity The function invoked per iteration.
Returns:
Array -Returns the new flattened array.
- Since:
- 4.7.0
Example
function duplicate(n) { return [[[n, n]]]; } _.flatMapDeep([1, 2], duplicate); // => [1, 1, 2, 2]
-
static flatMapDepth(collection, iterateeopt, depthopt) → {Array}
-
This method is like
_.flatMap
except that it recursively flattens the
mapped results up todepth
times.Parameters:
Name Type Attributes Default Description collection
Array | Object The collection to iterate over.
iteratee
function <optional>
_.identity The function invoked per iteration.
depth
number <optional>
1 The maximum recursion depth.
Returns:
Array -Returns the new flattened array.
- Since:
- 4.7.0
Example
function duplicate(n) { return [[[n, n]]]; } _.flatMapDepth([1, 2], duplicate, 2); // => [[1, 1], [2, 2]]
-
static flatten(array) → {Array}
-
Flattens
array
a single level deep.Parameters:
Name Type Description array
Array The array to flatten.
Returns:
Array -Returns the new flattened array.
- Since:
- 0.1.0
Example
_.flatten([1, [2, [3, [4]], 5]]); // => [1, 2, [3, [4]], 5]
-
static flattenDeep(array) → {Array}
-
Recursively flattens
array
.Parameters:
Name Type Description array
Array The array to flatten.
Returns:
Array -Returns the new flattened array.
- Since:
- 3.0.0
Example
_.flattenDeep([1, [2, [3, [4]], 5]]); // => [1, 2, 3, 4, 5]
-
static flattenDepth(array, depthopt) → {Array}
-
Recursively flatten
array
up todepth
times.Parameters:
Name Type Attributes Default Description array
Array The array to flatten.
depth
number <optional>
1 The maximum recursion depth.
Returns:
Array -Returns the new flattened array.
- Since:
- 4.4.0
Example
var array = [1, [2, [3, [4]], 5]]; _.flattenDepth(array, 1); // => [1, 2, [3, [4]], 5] _.flattenDepth(array, 2); // => [1, 2, 3, [4], 5]
-
static flip(func) → {function}
-
Creates a function that invokes
func
with arguments reversed.Parameters:
Name Type Description func
function The function to flip arguments for.
Returns:
function -Returns the new flipped function.
- Since:
- 4.0.0
Example
var flipped = _.flip(function() { return _.toArray(arguments); }); flipped('a', 'b', 'c', 'd'); // => ['d', 'c', 'b', 'a']
-
static forIn(object, iterateeopt) → {Object}
-
Iterates over own and inherited enumerable string keyed properties of an
object and invokesiteratee
for each property. The iteratee is invoked
with three arguments: (value, key, object). Iteratee functions may exit
iteration early by explicitly returningfalse
.Parameters:
Name Type Attributes Default Description object
Object The object to iterate over.
iteratee
function <optional>
_.identity The function invoked per iteration.
Returns:
Object -Returns
object
.- Since:
- 0.3.0
- See:
Example
function Foo() { this.a = 1; this.b = 2; } Foo.prototype.c = 3; _.forIn(new Foo, function(value, key) { console.log(key); }); // => Logs 'a', 'b', then 'c' (iteration order is not guaranteed).
-
static forInRight(object, iterateeopt) → {Object}
-
This method is like
_.forIn
except that it iterates over properties of
object
in the opposite order.Parameters:
Name Type Attributes Default Description object
Object The object to iterate over.
iteratee
function <optional>
_.identity The function invoked per iteration.
Returns:
Object -Returns
object
.- Since:
- 2.0.0
- See:
Example
function Foo() { this.a = 1; this.b = 2; } Foo.prototype.c = 3; _.forInRight(new Foo, function(value, key) { console.log(key); }); // => Logs 'c', 'b', then 'a' assuming `_.forIn` logs 'a', 'b', then 'c'.
-
static forOwn(object, iterateeopt) → {Object}
-
Iterates over own enumerable string keyed properties of an object and
invokesiteratee
for each property. The iteratee is invoked with three
arguments: (value, key, object). Iteratee functions may exit iteration
early by explicitly returningfalse
.Parameters:
Name Type Attributes Default Description object
Object The object to iterate over.
iteratee
function <optional>
_.identity The function invoked per iteration.
Returns:
Object -Returns
object
.- Since:
- 0.3.0
- See:
Example
function Foo() { this.a = 1; this.b = 2; } Foo.prototype.c = 3; _.forOwn(new Foo, function(value, key) { console.log(key); }); // => Logs 'a' then 'b' (iteration order is not guaranteed).
-
static forOwnRight(object, iterateeopt) → {Object}
-
This method is like
_.forOwn
except that it iterates over properties of
object
in the opposite order.Parameters:
Name Type Attributes Default Description object
Object The object to iterate over.
iteratee
function <optional>
_.identity The function invoked per iteration.
Returns:
Object -Returns
object
.- Since:
- 2.0.0
- See:
Example
function Foo() { this.a = 1; this.b = 2; } Foo.prototype.c = 3; _.forOwnRight(new Foo, function(value, key) { console.log(key); }); // => Logs 'b' then 'a' assuming `_.forOwn` logs 'a' then 'b'.
-
static fromPairs(pairs) → {Object}
-
The inverse of
_.toPairs
; this method returns an object composed
from key-valuepairs
.Parameters:
Name Type Description pairs
Array The key-value pairs.
Returns:
Object -Returns the new object.
- Since:
- 4.0.0
Example
_.fromPairs([['a', 1], ['b', 2]]); // => { 'a': 1, 'b': 2 }
-
static functions(object) → {Array}
-
Creates an array of function property names from own enumerable properties
ofobject
.Parameters:
Name Type Description object
Object The object to inspect.
Returns:
Array -Returns the function names.
- Since:
- 0.1.0
- See:
Example
function Foo() { this.a = _.constant('a'); this.b = _.constant('b'); } Foo.prototype.c = _.constant('c'); _.functions(new Foo); // => ['a', 'b']
-
static functionsIn(object) → {Array}
-
Creates an array of function property names from own and inherited
enumerable properties ofobject
.Parameters:
Name Type Description object
Object The object to inspect.
Returns:
Array -Returns the function names.
- Since:
- 4.0.0
- See:
Example
function Foo() { this.a = _.constant('a'); this.b = _.constant('b'); } Foo.prototype.c = _.constant('c'); _.functionsIn(new Foo); // => ['a', 'b', 'c']
-
static get(object, path, defaultValueopt) → {*}
-
Gets the value at
path
ofobject
. If the resolved value is
undefined
, thedefaultValue
is returned in its place.Parameters:
Name Type Attributes Description object
Object The object to query.
path
Array | string The path of the property to get.
defaultValue
* <optional>
The value returned for
undefined
resolved values.Returns:
* -Returns the resolved value.
- Since:
- 3.7.0
Example
var object = { 'a': [{ 'b': { 'c': 3 } }] }; _.get(object, 'a[0].b.c'); // => 3 _.get(object, ['a', '0', 'b', 'c']); // => 3 _.get(object, 'a.b.c', 'default'); // => 'default'
-
static has(object, path) → {boolean}
-
Checks if
path
is a direct property ofobject
.Parameters:
Name Type Description object
Object The object to query.
path
Array | string The path to check.
Returns:
boolean -Returns
true
ifpath
exists, elsefalse
.- Since:
- 0.1.0
Example
var object = { 'a': { 'b': 2 } }; var other = _.create({ 'a': _.create({ 'b': 2 }) }); _.has(object, 'a'); // => true _.has(object, 'a.b'); // => true _.has(object, ['a', 'b']); // => true _.has(other, 'a'); // => false
-
static hasIn(object, path) → {boolean}
-
Checks if
path
is a direct or inherited property ofobject
.Parameters:
Name Type Description object
Object The object to query.
path
Array | string The path to check.
Returns:
boolean -Returns
true
ifpath
exists, elsefalse
.- Since:
- 4.0.0
Example
var object = _.create({ 'a': _.create({ 'b': 2 }) }); _.hasIn(object, 'a'); // => true _.hasIn(object, 'a.b'); // => true _.hasIn(object, ['a', 'b']); // => true _.hasIn(object, 'b'); // => false
-
static identity(value) → {*}
-
This method returns the first argument it receives.
Parameters:
Name Type Description value
* Any value.
Returns:
* -Returns
value
.- Since:
- 0.1.0
Example
var object = { 'a': 1 }; console.log(_.identity(object) === object); // => true
-
static inRange(number, startopt, end) → {boolean}
-
Checks if
n
is betweenstart
and up to, but not including,end
. If
end
is not specified, it's set tostart
withstart
then set to0
.
Ifstart
is greater thanend
the params are swapped to support
negative ranges.Parameters:
Name Type Attributes Default Description number
number The number to check.
start
number <optional>
0 The start of the range.
end
number The end of the range.
Returns:
boolean -Returns
true
ifnumber
is in the range, elsefalse
.- Since:
- 3.3.0
- See:
-
- _.range, _.rangeRight
Example
_.inRange(3, 2, 4); // => true _.inRange(4, 8); // => true _.inRange(4, 2); // => false _.inRange(2, 2); // => false _.inRange(1.2, 2); // => true _.inRange(5.2, 4); // => false _.inRange(-3, -2, -6); // => true
-
static includes(collection, value, fromIndexopt) → {boolean}
-
Checks if
value
is incollection
. Ifcollection
is a string, it's
checked for a substring ofvalue
, otherwise
SameValueZero
is used for equality comparisons. IffromIndex
is negative, it's used as
the offset from the end ofcollection
.Parameters:
Name Type Attributes Default Description collection
Array | Object | string The collection to inspect.
value
* The value to search for.
fromIndex
number <optional>
0 The index to search from.
Returns:
boolean -Returns
true
ifvalue
is found, elsefalse
.- Since:
- 0.1.0
Example
_.includes([1, 2, 3], 1); // => true _.includes([1, 2, 3], 1, 2); // => false _.includes({ 'a': 1, 'b': 2 }, 1); // => true _.includes('abcd', 'bc'); // => true
-
static indexOf(array, value, fromIndexopt) → {number}
-
Gets the index at which the first occurrence of
value
is found inarray
usingSameValueZero
for equality comparisons. IffromIndex
is negative, it's used as the
offset from the end ofarray
.Parameters:
Name Type Attributes Default Description array
Array The array to inspect.
value
* The value to search for.
fromIndex
number <optional>
0 The index to search from.
Returns:
number -Returns the index of the matched value, else
-1
.- Since:
- 0.1.0
Example
_.indexOf([1, 2, 1, 2], 2); // => 1 // Search from the `fromIndex`. _.indexOf([1, 2, 1, 2], 2, 2); // => 3
-
static initial(array) → {Array}
-
Gets all but the last element of
array
.Parameters:
Name Type Description array
Array The array to query.
Returns:
Array -Returns the slice of
array
.- Since:
- 0.1.0
Example
_.initial([1, 2, 3]); // => [1, 2]
-
static isArrayLike(value) → {boolean}
-
Checks if
value
is array-like. A value is considered array-like if it's
not a function and has avalue.length
that's an integer greater than or
equal to0
and less than or equal toNumber.MAX_SAFE_INTEGER
.Parameters:
Name Type Description value
* The value to check.
Returns:
boolean -Returns
true
ifvalue
is array-like, elsefalse
.- Since:
- 4.0.0
Example
_.isArrayLike([1, 2, 3]); // => true _.isArrayLike(document.body.children); // => true _.isArrayLike('abc'); // => true _.isArrayLike(_.noop); // => false
-
static isArrayLikeObject(value) → {boolean}
-
This method is like
_.isArrayLike
except that it also checks ifvalue
is an object.Parameters:
Name Type Description value
* The value to check.
Returns:
boolean -Returns
true
ifvalue
is an array-like object,
elsefalse
.- Since:
- 4.0.0
Example
_.isArrayLikeObject([1, 2, 3]); // => true _.isArrayLikeObject(document.body.children); // => true _.isArrayLikeObject('abc'); // => false _.isArrayLikeObject(_.noop); // => false
-
static isBoolean(value) → {boolean}
-
Checks if
value
is classified as a boolean primitive or object.Parameters:
Name Type Description value
* The value to check.
Returns:
boolean -Returns
true
ifvalue
is a boolean, elsefalse
.- Since:
- 0.1.0
Example
_.isBoolean(false); // => true _.isBoolean(null); // => false
-
static isElement(value) → {boolean}
-
Checks if
value
is likely a DOM element.Parameters:
Name Type Description value
* The value to check.
Returns:
boolean -Returns
true
ifvalue
is a DOM element, elsefalse
.- Since:
- 0.1.0
Example
_.isElement(document.body); // => true _.isElement('<body>'); // => false
-
static isEmpty(value) → {boolean}
-
Checks if
value
is an empty object, collection, map, or set.Objects are considered empty if they have no own enumerable string keyed
properties.Array-like values such as
arguments
objects, arrays, buffers, strings, or
jQuery-like collections are considered empty if they have alength
of0
.
Similarly, maps and sets are considered empty if they have asize
of0
.Parameters:
Name Type Description value
* The value to check.
Returns:
boolean -Returns
true
ifvalue
is empty, elsefalse
.- Since:
- 0.1.0
Example
_.isEmpty(null); // => true _.isEmpty(true); // => true _.isEmpty(1); // => true _.isEmpty([1, 2, 3]); // => false _.isEmpty({ 'a': 1 }); // => false
-
static isEqual(value, other) → {boolean}
-
Performs a deep comparison between two values to determine if they are
equivalent.Note: This method supports comparing arrays, array buffers, booleans,
date objects, error objects, maps, numbers,Object
objects, regexes,
sets, strings, symbols, and typed arrays.Object
objects are compared
by their own, not inherited, enumerable properties. Functions and DOM
nodes are compared by strict equality, i.e.===
.Parameters:
Name Type Description value
* The value to compare.
other
* The other value to compare.
Returns:
boolean -Returns
true
if the values are equivalent, elsefalse
.- Since:
- 0.1.0
Example
var object = { 'a': 1 }; var other = { 'a': 1 }; _.isEqual(object, other); // => true object === other; // => false
-
static isEqualWith(value, other, customizeropt) → {boolean}
-
This method is like
_.isEqual
except that it acceptscustomizer
which
is invoked to compare values. Ifcustomizer
returnsundefined
, comparisons
are handled by the method instead. Thecustomizer
is invoked with up to
six arguments: (objValue, othValue [, index|key, object, other, stack]).Parameters:
Name Type Attributes Description value
* The value to compare.
other
* The other value to compare.
customizer
function <optional>
The function to customize comparisons.
Returns:
boolean -Returns
true
if the values are equivalent, elsefalse
.- Since:
- 4.0.0
Example
function isGreeting(value) { return /^h(?:i|ello)$/.test(value); } function customizer(objValue, othValue) { if (isGreeting(objValue) && isGreeting(othValue)) { return true; } } var array = ['hello', 'goodbye']; var other = ['hi', 'goodbye']; _.isEqualWith(array, other, customizer); // => true
-
static isError(value) → {boolean}
-
Checks if
value
is anError
,EvalError
,RangeError
,ReferenceError
,
SyntaxError
,TypeError
, orURIError
object.Parameters:
Name Type Description value
* The value to check.
Returns:
boolean -Returns
true
ifvalue
is an error object, elsefalse
.- Since:
- 3.0.0
Example
_.isError(new Error); // => true _.isError(Error); // => false
-
static isFinite(value) → {boolean}
-
Checks if
value
is a finite primitive number.Note: This method is based on
Number.isFinite
.Parameters:
Name Type Description value
* The value to check.
Returns:
boolean -Returns
true
ifvalue
is a finite number, elsefalse
.- Since:
- 0.1.0
Example
_.isFinite(3); // => true _.isFinite(Number.MIN_VALUE); // => true _.isFinite(Infinity); // => false _.isFinite('3'); // => false
-
static isFunction(value) → {boolean}
-
Checks if
value
is classified as aFunction
object.Parameters:
Name Type Description value
* The value to check.
Returns:
boolean -Returns
true
ifvalue
is a function, elsefalse
.- Since:
- 0.1.0
Example
_.isFunction(_); // => true _.isFunction(/abc/); // => false
-
static isInteger(value) → {boolean}
-
Checks if
value
is an integer.Note: This method is based on
Number.isInteger
.Parameters:
Name Type Description value
* The value to check.
Returns:
boolean -Returns
true
ifvalue
is an integer, elsefalse
.- Since:
- 4.0.0
Example
_.isInteger(3); // => true _.isInteger(Number.MIN_VALUE); // => false _.isInteger(Infinity); // => false _.isInteger('3'); // => false
-
static isLength(value) → {boolean}
-
Checks if
value
is a valid array-like length.Note: This method is loosely based on
ToLength
.Parameters:
Name Type Description value
* The value to check.
Returns:
boolean -Returns
true
ifvalue
is a valid length, elsefalse
.- Since:
- 4.0.0
Example
_.isLength(3); // => true _.isLength(Number.MIN_VALUE); // => false _.isLength(Infinity); // => false _.isLength('3'); // => false
-
static isMatch(object, source) → {boolean}
-
Performs a partial deep comparison between
object
andsource
to
determine ifobject
contains equivalent property values.Note: This method is equivalent to
_.matches
whensource
is
partially applied.Partial comparisons will match empty array and empty object
source
values against any array or object value, respectively. See_.isEqual
for a list of supported value comparisons.Parameters:
Name Type Description object
Object The object to inspect.
source
Object The object of property values to match.
Returns:
boolean -Returns
true
ifobject
is a match, elsefalse
.- Since:
- 3.0.0
Example
var object = { 'a': 1, 'b': 2 }; _.isMatch(object, { 'b': 2 }); // => true _.isMatch(object, { 'b': 1 }); // => false
-
static isMatchWith(object, source, customizeropt) → {boolean}
-
This method is like
_.isMatch
except that it acceptscustomizer
which
is invoked to compare values. Ifcustomizer
returnsundefined
, comparisons
are handled by the method instead. Thecustomizer
is invoked with five
arguments: (objValue, srcValue, index|key, object, source).Parameters:
Name Type Attributes Description object
Object The object to inspect.
source
Object The object of property values to match.
customizer
function <optional>
The function to customize comparisons.
Returns:
boolean -Returns
true
ifobject
is a match, elsefalse
.- Since:
- 4.0.0
Example
function isGreeting(value) { return /^h(?:i|ello)$/.test(value); } function customizer(objValue, srcValue) { if (isGreeting(objValue) && isGreeting(srcValue)) { return true; } } var object = { 'greeting': 'hello' }; var source = { 'greeting': 'hi' }; _.isMatchWith(object, source, customizer); // => true
-
static isNaN(value) → {boolean}
-
Checks if
value
isNaN
.Note: This method is based on
Number.isNaN
and is not the same as
globalisNaN
which returnstrue
for
undefined
and other non-number values.Parameters:
Name Type Description value
* The value to check.
Returns:
boolean -Returns
true
ifvalue
isNaN
, elsefalse
.- Since:
- 0.1.0
Example
_.isNaN(NaN); // => true _.isNaN(new Number(NaN)); // => true isNaN(undefined); // => true _.isNaN(undefined); // => false
-
static isNative(value) → {boolean}
-
Checks if
value
is a pristine native function.Note: This method can't reliably detect native functions in the presence
of the core-js package because core-js circumvents this kind of detection.
Despite multiple requests, the core-js maintainer has made it clear: any
attempt to fix the detection will be obstructed. As a result, we're left
with little choice but to throw an error. Unfortunately, this also affects
packages, like babel-polyfill,
which rely on core-js.Parameters:
Name Type Description value
* The value to check.
Returns:
boolean -Returns
true
ifvalue
is a native function,
elsefalse
.- Since:
- 3.0.0
Example
_.isNative(Array.prototype.push); // => true _.isNative(_); // => false
-
static isNil(value) → {boolean}
-
Checks if
value
isnull
orundefined
.Parameters:
Name Type Description value
* The value to check.
Returns:
boolean -Returns
true
ifvalue
is nullish, elsefalse
.- Since:
- 4.0.0
Example
_.isNil(null); // => true _.isNil(void 0); // => true _.isNil(NaN); // => false
-
static isNull(value) → {boolean}
-
Checks if
value
isnull
.Parameters:
Name Type Description value
* The value to check.
Returns:
boolean -Returns
true
ifvalue
isnull
, elsefalse
.- Since:
- 0.1.0
Example
_.isNull(null); // => true _.isNull(void 0); // => false
-
static isNumber(value) → {boolean}
-
Checks if
value
is classified as aNumber
primitive or object.Note: To exclude
Infinity
,-Infinity
, andNaN
, which are
classified as numbers, use the_.isFinite
method.Parameters:
Name Type Description value
* The value to check.
Returns:
boolean -Returns
true
ifvalue
is a number, elsefalse
.- Since:
- 0.1.0
Example
_.isNumber(3); // => true _.isNumber(Number.MIN_VALUE); // => true _.isNumber(Infinity); // => true _.isNumber('3'); // => false
-
static isObject(value) → {boolean}
-
Checks if
value
is the
language type
ofObject
. (e.g. arrays, functions, objects, regexes,new Number(0)
, andnew String('')
)Parameters:
Name Type Description value
* The value to check.
Returns:
boolean -Returns
true
ifvalue
is an object, elsefalse
.- Since:
- 0.1.0
Example
_.isObject({}); // => true _.isObject([1, 2, 3]); // => true _.isObject(_.noop); // => true _.isObject(null); // => false
-
static isObjectLike(value) → {boolean}
-
Checks if
value
is object-like. A value is object-like if it's notnull
and has atypeof
result of "object".Parameters:
Name Type Description value
* The value to check.
Returns:
boolean -Returns
true
ifvalue
is object-like, elsefalse
.- Since:
- 4.0.0
Example
_.isObjectLike({}); // => true _.isObjectLike([1, 2, 3]); // => true _.isObjectLike(_.noop); // => false _.isObjectLike(null); // => false
-
static isPlainObject(value) → {boolean}
-
Checks if
value
is a plain object, that is, an object created by the
Object
constructor or one with a[[Prototype]]
ofnull
.Parameters:
Name Type Description value
* The value to check.
Returns:
boolean -Returns
true
ifvalue
is a plain object, elsefalse
.- Since:
- 0.8.0
Example
function Foo() { this.a = 1; } _.isPlainObject(new Foo); // => false _.isPlainObject([1, 2, 3]); // => false _.isPlainObject({ 'x': 0, 'y': 0 }); // => true _.isPlainObject(Object.create(null)); // => true
-
static isSafeInteger(value) → {boolean}
-
Checks if
value
is a safe integer. An integer is safe if it's an IEEE-754
double precision number which isn't the result of a rounded unsafe integer.Note: This method is based on
Number.isSafeInteger
.Parameters:
Name Type Description value
* The value to check.
Returns:
boolean -Returns
true
ifvalue
is a safe integer, elsefalse
.- Since:
- 4.0.0
Example
_.isSafeInteger(3); // => true _.isSafeInteger(Number.MIN_VALUE); // => false _.isSafeInteger(Infinity); // => false _.isSafeInteger('3'); // => false
-
static isString(value) → {boolean}
-
Checks if
value
is classified as aString
primitive or object.Parameters:
Name Type Description value
* The value to check.
Returns:
boolean -Returns
true
ifvalue
is a string, elsefalse
.- Since:
- 0.1.0
Example
_.isString('abc'); // => true _.isString(1); // => false
-
static isSymbol(value) → {boolean}
-
Checks if
value
is classified as aSymbol
primitive or object.Parameters:
Name Type Description value
* The value to check.
Returns:
boolean -Returns
true
ifvalue
is a symbol, elsefalse
.- Since:
- 4.0.0
Example
_.isSymbol(Symbol.iterator); // => true _.isSymbol('abc'); // => false
-
static isUndefined(value) → {boolean}
-
Checks if
value
isundefined
.Parameters:
Name Type Description value
* The value to check.
Returns:
boolean -Returns
true
ifvalue
isundefined
, elsefalse
.- Since:
- 0.1.0
Example
_.isUndefined(void 0); // => true _.isUndefined(null); // => false
-
static isWeakMap(value) → {boolean}
-
Checks if
value
is classified as aWeakMap
object.Parameters:
Name Type Description value
* The value to check.
Returns:
boolean -Returns
true
ifvalue
is a weak map, elsefalse
.- Since:
- 4.3.0
Example
_.isWeakMap(new WeakMap); // => true _.isWeakMap(new Map); // => false
-
static isWeakSet(value) → {boolean}
-
Checks if
value
is classified as aWeakSet
object.Parameters:
Name Type Description value
* The value to check.
Returns:
boolean -Returns
true
ifvalue
is a weak set, elsefalse
.- Since:
- 4.3.0
Example
_.isWeakSet(new WeakSet); // => true _.isWeakSet(new Set); // => false
-
static iteratee(funcopt) → {function}
-
Creates a function that invokes
func
with the arguments of the created
function. Iffunc
is a property name, the created function returns the
property value for a given element. Iffunc
is an array or object, the
created function returnstrue
for elements that contain the equivalent
source properties, otherwise it returnsfalse
.Parameters:
Name Type Attributes Default Description func
* <optional>
_.identity The value to convert to a callback.
Returns:
function -Returns the callback.
- Since:
- 4.0.0
Example
var users = [ { 'user': 'barney', 'age': 36, 'active': true }, { 'user': 'fred', 'age': 40, 'active': false } ]; // The `_.matches` iteratee shorthand. _.filter(users, _.iteratee({ 'user': 'barney', 'active': true })); // => [{ 'user': 'barney', 'age': 36, 'active': true }] // The `_.matchesProperty` iteratee shorthand. _.filter(users, _.iteratee(['user', 'fred'])); // => [{ 'user': 'fred', 'age': 40 }] // The `_.property` iteratee shorthand. _.map(users, _.iteratee('user')); // => ['barney', 'fred'] // Create custom iteratee shorthands. _.iteratee = _.wrap(_.iteratee, function(iteratee, func) { return !_.isRegExp(func) ? iteratee(func) : function(string) { return func.test(string); }; }); _.filter(['abc', 'def'], /ef/); // => ['def']
-
static join(array, separatoropt) → {string}
-
Converts all elements in
array
into a string separated byseparator
.Parameters:
Name Type Attributes Default Description array
Array The array to convert.
separator
string <optional>
',' The element separator.
Returns:
string -Returns the joined string.
- Since:
- 4.0.0
Example
_.join(['a', 'b', 'c'], '~'); // => 'a~b~c'
-
static keys(object) → {Array}
-
Creates an array of the own enumerable property names of
object
.Note: Non-object values are coerced to objects. See the
ES spec
for more details.Parameters:
Name Type Description object
Object The object to query.
Returns:
Array -Returns the array of property names.
- Since:
- 0.1.0
Example
function Foo() { this.a = 1; this.b = 2; } Foo.prototype.c = 3; _.keys(new Foo); // => ['a', 'b'] (iteration order is not guaranteed) _.keys('hi'); // => ['0', '1']
-
static keysIn(object) → {Array}
-
Creates an array of the own and inherited enumerable property names of
object
.Note: Non-object values are coerced to objects.
Parameters:
Name Type Description object
Object The object to query.
Returns:
Array -Returns the array of property names.
- Since:
- 3.0.0
Example
function Foo() { this.a = 1; this.b = 2; } Foo.prototype.c = 3; _.keysIn(new Foo); // => ['a', 'b', 'c'] (iteration order is not guaranteed)
-
static last(array) → {*}
-
Gets the last element of
array
.Parameters:
Name Type Description array
Array The array to query.
Returns:
* -Returns the last element of
array
.- Since:
- 0.1.0
Example
_.last([1, 2, 3]); // => 3
-
static lastIndexOf(array, value, fromIndexopt) → {number}
-
This method is like
_.indexOf
except that it iterates over elements of
array
from right to left.Parameters:
Name Type Attributes Default Description array
Array The array to inspect.
value
* The value to search for.
fromIndex
number <optional>
array.length-1 The index to search from.
Returns:
number -Returns the index of the matched value, else
-1
.- Since:
- 0.1.0
Example
_.lastIndexOf([1, 2, 1, 2], 2); // => 3 // Search from the `fromIndex`. _.lastIndexOf([1, 2, 1, 2], 2, 2); // => 1
-
static map(collection, iterateeopt) → {Array}
-
Creates an array of values by running each element in
collection
thru
iteratee
. The iteratee is invoked with three arguments:
(value, index|key, collection).Many lodash methods are guarded to work as iteratees for methods like
_.every
,_.filter
,_.map
,_.mapValues
,_.reject
, and_.some
.The guarded methods are:
ary
,chunk
,curry
,curryRight
,drop
,dropRight
,every
,
fill
,invert
,parseInt
,random
,range
,rangeRight
,repeat
,
sampleSize
,slice
,some
,sortBy
,split
,take
,takeRight
,
template
,trim
,trimEnd
,trimStart
, andwords
Parameters:
Name Type Attributes Default Description collection
Array | Object The collection to iterate over.
iteratee
function <optional>
_.identity The function invoked per iteration.
Returns:
Array -Returns the new mapped array.
- Since:
- 0.1.0
Example
function square(n) { return n * n; } _.map([4, 8], square); // => [16, 64] _.map({ 'a': 4, 'b': 8 }, square); // => [16, 64] (iteration order is not guaranteed) var users = [ { 'user': 'barney' }, { 'user': 'fred' } ]; // The `_.property` iteratee shorthand. _.map(users, 'user'); // => ['barney', 'fred']
-
static mapKeys(object, iterateeopt) → {Object}
-
The opposite of
_.mapValues
; this method creates an object with the
same values asobject
and keys generated by running each own enumerable
string keyed property ofobject
thruiteratee
. The iteratee is invoked
with three arguments: (value, key, object).Parameters:
Name Type Attributes Default Description object
Object The object to iterate over.
iteratee
function <optional>
_.identity The function invoked per iteration.
Returns:
Object -Returns the new mapped object.
- Since:
- 3.8.0
- See:
Example
_.mapKeys({ 'a': 1, 'b': 2 }, function(value, key) { return key + value; }); // => { 'a1': 1, 'b2': 2 }
-
static mapValues(object, iterateeopt) → {Object}
-
Creates an object with the same keys as
object
and values generated
by running each own enumerable string keyed property ofobject
thru
iteratee
. The iteratee is invoked with three arguments:
(value, key, object).Parameters:
Name Type Attributes Default Description object
Object The object to iterate over.
iteratee
function <optional>
_.identity The function invoked per iteration.
Returns:
Object -Returns the new mapped object.
- Since:
- 2.4.0
- See:
Example
var users = { 'fred': { 'user': 'fred', 'age': 40 }, 'pebbles': { 'user': 'pebbles', 'age': 1 } }; _.mapValues(users, function(o) { return o.age; }); // => { 'fred': 40, 'pebbles': 1 } (iteration order is not guaranteed) // The `_.property` iteratee shorthand. _.mapValues(users, 'age'); // => { 'fred': 40, 'pebbles': 1 } (iteration order is not guaranteed)
-
static matches(source) → {function}
-
Creates a function that performs a partial deep comparison between a given
object andsource
, returningtrue
if the given object has equivalent
property values, elsefalse
.Note: The created function is equivalent to
_.isMatch
withsource
partially applied.Partial comparisons will match empty array and empty object
source
values against any array or object value, respectively. See_.isEqual
for a list of supported value comparisons.Parameters:
Name Type Description source
Object The object of property values to match.
Returns:
function -Returns the new spec function.
- Since:
- 3.0.0
Example
var objects = [ { 'a': 1, 'b': 2, 'c': 3 }, { 'a': 4, 'b': 5, 'c': 6 } ]; _.filter(objects, _.matches({ 'a': 4, 'c': 6 })); // => [{ 'a': 4, 'b': 5, 'c': 6 }]
-
static matchesProperty(path, srcValue) → {function}
-
Creates a function that performs a partial deep comparison between the
value atpath
of a given object tosrcValue
, returningtrue
if the
object value is equivalent, elsefalse
.Note: Partial comparisons will match empty array and empty object
srcValue
values against any array or object value, respectively. See
_.isEqual
for a list of supported value comparisons.Parameters:
Name Type Description path
Array | string The path of the property to get.
srcValue
* The value to match.
Returns:
function -Returns the new spec function.
- Since:
- 3.2.0
Example
var objects = [ { 'a': 1, 'b': 2, 'c': 3 }, { 'a': 4, 'b': 5, 'c': 6 } ]; _.find(objects, _.matchesProperty('a', 4)); // => { 'a': 4, 'b': 5, 'c': 6 }
-
static max(array) → {*}
-
Computes the maximum value of
array
. Ifarray
is empty or falsey,
undefined
is returned.Parameters:
Name Type Description array
Array The array to iterate over.
Returns:
* -Returns the maximum value.
- Since:
- 0.1.0
Example
_.max([4, 2, 8, 6]); // => 8 _.max([]); // => undefined
-
static maxBy(array, iterateeopt) → {*}
-
This method is like
_.max
except that it acceptsiteratee
which is
invoked for each element inarray
to generate the criterion by which
the value is ranked. The iteratee is invoked with one argument: (value).Parameters:
Name Type Attributes Default Description array
Array The array to iterate over.
iteratee
function <optional>
_.identity The iteratee invoked per element.
Returns:
* -Returns the maximum value.
- Since:
- 4.0.0
Example
var objects = [{ 'n': 1 }, { 'n': 2 }]; _.maxBy(objects, function(o) { return o.n; }); // => { 'n': 2 } // The `_.property` iteratee shorthand. _.maxBy(objects, 'n'); // => { 'n': 2 }
-
static mean(array) → {number}
-
Computes the mean of the values in
array
.Parameters:
Name Type Description array
Array The array to iterate over.
Returns:
number -Returns the mean.
- Since:
- 4.0.0
Example
_.mean([4, 2, 8, 6]); // => 5
-
static meanBy(array, iterateeopt) → {number}
-
This method is like
_.mean
except that it acceptsiteratee
which is
invoked for each element inarray
to generate the value to be averaged.
The iteratee is invoked with one argument: (value).Parameters:
Name Type Attributes Default Description array
Array The array to iterate over.
iteratee
function <optional>
_.identity The iteratee invoked per element.
Returns:
number -Returns the mean.
- Since:
- 4.7.0
Example
var objects = [{ 'n': 4 }, { 'n': 2 }, { 'n': 8 }, { 'n': 6 }]; _.meanBy(objects, function(o) { return o.n; }); // => 5 // The `_.property` iteratee shorthand. _.meanBy(objects, 'n'); // => 5
-
static memoize(func, resolveropt) → {function}
-
Creates a function that memoizes the result of
func
. Ifresolver
is
provided, it determines the cache key for storing the result based on the
arguments provided to the memoized function. By default, the first argument
provided to the memoized function is used as the map cache key. Thefunc
is invoked with thethis
binding of the memoized function.Note: The cache is exposed as the
cache
property on the memoized
function. Its creation may be customized by replacing the_.memoize.Cache
constructor with one whose instances implement the
Map
method interface ofclear
,delete
,get
,has
, andset
.Parameters:
Name Type Attributes Description func
function The function to have its output memoized.
resolver
function <optional>
The function to resolve the cache key.
Returns:
function -Returns the new memoized function.
- Since:
- 0.1.0
Example
var object = { 'a': 1, 'b': 2 }; var other = { 'c': 3, 'd': 4 }; var values = _.memoize(_.values); values(object); // => [1, 2] values(other); // => [3, 4] object.a = 2; values(object); // => [1, 2] // Modify the result cache. values.cache.set(object, ['a', 'b']); values(object); // => ['a', 'b'] // Replace `_.memoize.Cache`. _.memoize.Cache = WeakMap;
-
static min(array) → {*}
-
Computes the minimum value of
array
. Ifarray
is empty or falsey,
undefined
is returned.Parameters:
Name Type Description array
Array The array to iterate over.
Returns:
* -Returns the minimum value.
- Since:
- 0.1.0
Example
_.min([4, 2, 8, 6]); // => 2 _.min([]); // => undefined
-
static minBy(array, iterateeopt) → {*}
-
This method is like
_.min
except that it acceptsiteratee
which is
invoked for each element inarray
to generate the criterion by which
the value is ranked. The iteratee is invoked with one argument: (value).Parameters:
Name Type Attributes Default Description array
Array The array to iterate over.
iteratee
function <optional>
_.identity The iteratee invoked per element.
Returns:
* -Returns the minimum value.
- Since:
- 4.0.0
Example
var objects = [{ 'n': 1 }, { 'n': 2 }]; _.minBy(objects, function(o) { return o.n; }); // => { 'n': 1 } // The `_.property` iteratee shorthand. _.minBy(objects, 'n'); // => { 'n': 1 }
-
static mixin(objectopt, source, optionsopt) → {function|Object}
-
Adds all own enumerable string keyed function properties of a source
object to the destination object. Ifobject
is a function, then methods
are added to its prototype as well.Note: Use
_.runInContext
to create a pristinelodash
function to
avoid conflicts caused by modifying the original.Parameters:
Name Type Attributes Default Description object
function | Object <optional>
lodash The destination object.
source
Object The object of functions to add.
options
Object <optional>
{} The options object.
Properties
Name Type Attributes Default Description chain
boolean <optional>
true Specify whether mixins are chainable.
Returns:
function | Object -Returns
object
.- Since:
- 0.1.0
Example
function vowels(string) { return _.filter(string, function(v) { return /[aeiou]/i.test(v); }); } _.mixin({ 'vowels': vowels }); _.vowels('fred'); // => ['e'] _('fred').vowels().value(); // => ['e'] _.mixin({ 'vowels': vowels }, { 'chain': false }); _('fred').vowels(); // => ['e']
-
static negate(predicate) → {function}
-
Creates a function that negates the result of the predicate
func
. The
func
predicate is invoked with thethis
binding and arguments of the
created function.Parameters:
Name Type Description predicate
function The predicate to negate.
Returns:
function -Returns the new negated function.
- Since:
- 3.0.0
Example
function isEven(n) { return n % 2 == 0; } _.filter([1, 2, 3, 4, 5, 6], _.negate(isEven)); // => [1, 3, 5]
-
static noConflict() → {function}
-
Reverts the
_
variable to its previous value and returns a reference to
thelodash
function.Returns:
function -Returns the
lodash
function.- Since:
- 0.1.0
Example
var lodash = _.noConflict();
-
static noop()
-
This method returns
undefined
.- Since:
- 2.3.0
Example
_.times(2, _.noop); // => [undefined, undefined]
-
static nth(array, nopt) → {*}
-
Gets the element at index
n
ofarray
. Ifn
is negative, the nth
element from the end is returned.Parameters:
Name Type Attributes Default Description array
Array The array to query.
n
number <optional>
0 The index of the element to return.
Returns:
* -Returns the nth element of
array
.- Since:
- 4.11.0
Example
var array = ['a', 'b', 'c', 'd']; _.nth(array, 1); // => 'b' _.nth(array, -2); // => 'c';
-
static nthArg(nopt) → {function}
-
Creates a function that gets the argument at index
n
. Ifn
is negative,
the nth argument from the end is returned.Parameters:
Name Type Attributes Default Description n
number <optional>
0 The index of the argument to return.
Returns:
function -Returns the new pass-thru function.
- Since:
- 4.0.0
Example
var func = _.nthArg(1); func('a', 'b', 'c', 'd'); // => 'b' var func = _.nthArg(-2); func('a', 'b', 'c', 'd'); // => 'c'
-
static omitBy(object, predicateopt) → {Object}
-
The opposite of
_.pickBy
; this method creates an object composed of
the own and inherited enumerable string keyed properties ofobject
that
predicate
doesn't return truthy for. The predicate is invoked with two
arguments: (value, key).Parameters:
Name Type Attributes Default Description object
Object The source object.
predicate
function <optional>
_.identity The function invoked per property.
Returns:
Object -Returns the new object.
- Since:
- 4.0.0
Example
var object = { 'a': 1, 'b': '2', 'c': 3 }; _.omitBy(object, _.isNumber); // => { 'b': '2' }
-
static once(func) → {function}
-
Creates a function that is restricted to invoking
func
once. Repeat calls
to the function return the value of the first invocation. Thefunc
is
invoked with thethis
binding and arguments of the created function.Parameters:
Name Type Description func
function The function to restrict.
Returns:
function -Returns the new restricted function.
- Since:
- 0.1.0
Example
var initialize = _.once(createApplication); initialize(); initialize(); // => `createApplication` is invoked once
-
static orderBy(collection, iterateesopt, ordersopt) → {Array}
-
This method is like
_.sortBy
except that it allows specifying the sort
orders of the iteratees to sort by. Iforders
is unspecified, all values
are sorted in ascending order. Otherwise, specify an order of "desc" for
descending or "asc" for ascending sort order of corresponding values.Parameters:
Name Type Attributes Default Description collection
Array | Object The collection to iterate over.
iteratees
Array.<Array> | Array.<function()> | Array.<Object> | Array.<string> <optional>
[_.identity] The iteratees to sort by.
orders
Array.<string> <optional>
The sort orders of
iteratees
.Returns:
Array -Returns the new sorted array.
- Since:
- 4.0.0
Example
var users = [ { 'user': 'fred', 'age': 48 }, { 'user': 'barney', 'age': 34 }, { 'user': 'fred', 'age': 40 }, { 'user': 'barney', 'age': 36 } ]; // Sort by `user` in ascending order and by `age` in descending order. _.orderBy(users, ['user', 'age'], ['asc', 'desc']); // => objects for [['barney', 36], ['barney', 34], ['fred', 48], ['fred', 40]]
-
static pad(stringopt, lengthopt, charsopt) → {string}
-
Pads
string
on the left and right sides if it's shorter thanlength
.
Padding characters are truncated if they can't be evenly divided bylength
.Parameters:
Name Type Attributes Default Description string
string <optional>
'' The string to pad.
length
number <optional>
0 The padding length.
chars
string <optional>
' ' The string used as padding.
Returns:
string -Returns the padded string.
- Since:
- 3.0.0
Example
_.pad('abc', 8); // => ' abc ' _.pad('abc', 8, '_-'); // => '_-abc_-_' _.pad('abc', 3); // => 'abc'
-
static padEnd(stringopt, lengthopt, charsopt) → {string}
-
Pads
string
on the right side if it's shorter thanlength
. Padding
characters are truncated if they exceedlength
.Parameters:
Name Type Attributes Default Description string
string <optional>
'' The string to pad.
length
number <optional>
0 The padding length.
chars
string <optional>
' ' The string used as padding.
Returns:
string -Returns the padded string.
- Since:
- 4.0.0
Example
_.padEnd('abc', 6); // => 'abc ' _.padEnd('abc', 6, '_-'); // => 'abc_-_' _.padEnd('abc', 3); // => 'abc'
-
static padStart(stringopt, lengthopt, charsopt) → {string}
-
Pads
string
on the left side if it's shorter thanlength
. Padding
characters are truncated if they exceedlength
.Parameters:
Name Type Attributes Default Description string
string <optional>
'' The string to pad.
length
number <optional>
0 The padding length.
chars
string <optional>
' ' The string used as padding.
Returns:
string -Returns the padded string.
- Since:
- 4.0.0
Example
_.padStart('abc', 6); // => ' abc' _.padStart('abc', 6, '_-'); // => '_-_abc' _.padStart('abc', 3); // => 'abc'
-
static parseInt(string, radixopt) → {number}
-
Converts
string
to an integer of the specified radix. Ifradix
is
undefined
or0
, aradix
of10
is used unlessvalue
is a
hexadecimal, in which case aradix
of16
is used.Note: This method aligns with the
ES5 implementation ofparseInt
.Parameters:
Name Type Attributes Default Description string
string The string to convert.
radix
number <optional>
10 The radix to interpret
value
by.Returns:
number -Returns the converted integer.
- Since:
- 1.1.0
Example
_.parseInt('08'); // => 8 _.map(['6', '08', '10'], _.parseInt); // => [6, 8, 10]
-
static pickBy(object, predicateopt) → {Object}
-
Creates an object composed of the
object
propertiespredicate
returns
truthy for. The predicate is invoked with two arguments: (value, key).Parameters:
Name Type Attributes Default Description object
Object The source object.
predicate
function <optional>
_.identity The function invoked per property.
Returns:
Object -Returns the new object.
- Since:
- 4.0.0
Example
var object = { 'a': 1, 'b': '2', 'c': 3 }; _.pickBy(object, _.isNumber); // => { 'a': 1, 'c': 3 }
-
static property(path) → {function}
-
Creates a function that returns the value at
path
of a given object.Parameters:
Name Type Description path
Array | string The path of the property to get.
Returns:
function -Returns the new accessor function.
- Since:
- 2.4.0
Example
var objects = [ { 'a': { 'b': 2 } }, { 'a': { 'b': 1 } } ]; _.map(objects, _.property('a.b')); // => [2, 1] _.map(_.sortBy(objects, _.property(['a', 'b'])), 'a.b'); // => [1, 2]
-
static propertyOf(object) → {function}
-
The opposite of
_.property
; this method creates a function that returns
the value at a given path ofobject
.Parameters:
Name Type Description object
Object The object to query.
Returns:
function -Returns the new accessor function.
- Since:
- 3.0.0
Example
var array = [0, 1, 2], object = { 'a': array, 'b': array, 'c': array }; _.map(['a[2]', 'c[0]'], _.propertyOf(object)); // => [2, 0] _.map([['a', '2'], ['c', '0']], _.propertyOf(object)); // => [2, 0]
-
static pullAll(array, values) → {Array}
-
This method is like
_.pull
except that it accepts an array of values to remove.Note: Unlike
_.difference
, this method mutatesarray
.Parameters:
Name Type Description array
Array The array to modify.
values
Array The values to remove.
Returns:
Array -Returns
array
.- Since:
- 4.0.0
Example
var array = ['a', 'b', 'c', 'a', 'b', 'c']; _.pullAll(array, ['a', 'c']); console.log(array); // => ['b', 'b']
-
static pullAllBy(array, values, iterateeopt) → {Array}
-
This method is like
_.pullAll
except that it acceptsiteratee
which is
invoked for each element ofarray
andvalues
to generate the criterion
by which they're compared. The iteratee is invoked with one argument: (value).Note: Unlike
_.differenceBy
, this method mutatesarray
.Parameters:
Name Type Attributes Default Description array
Array The array to modify.
values
Array The values to remove.
iteratee
function <optional>
_.identity The iteratee invoked per element.
Returns:
Array -Returns
array
.- Since:
- 4.0.0
Example
var array = [{ 'x': 1 }, { 'x': 2 }, { 'x': 3 }, { 'x': 1 }]; _.pullAllBy(array, [{ 'x': 1 }, { 'x': 3 }], 'x'); console.log(array); // => [{ 'x': 2 }]
-
static pullAllWith(array, values, comparatoropt) → {Array}
-
This method is like
_.pullAll
except that it acceptscomparator
which
is invoked to compare elements ofarray
tovalues
. The comparator is
invoked with two arguments: (arrVal, othVal).Note: Unlike
_.differenceWith
, this method mutatesarray
.Parameters:
Name Type Attributes Description array
Array The array to modify.
values
Array The values to remove.
comparator
function <optional>
The comparator invoked per element.
Returns:
Array -Returns
array
.- Since:
- 4.6.0
Example
var array = [{ 'x': 1, 'y': 2 }, { 'x': 3, 'y': 4 }, { 'x': 5, 'y': 6 }]; _.pullAllWith(array, [{ 'x': 3, 'y': 4 }], _.isEqual); console.log(array); // => [{ 'x': 1, 'y': 2 }, { 'x': 5, 'y': 6 }]
-
static random(loweropt, upperopt, floatingopt) → {number}
-
Produces a random number between the inclusive
lower
andupper
bounds.
If only one argument is provided a number between0
and the given number
is returned. Iffloating
istrue
, or eitherlower
orupper
are
floats, a floating-point number is returned instead of an integer.Note: JavaScript follows the IEEE-754 standard for resolving
floating-point values which can produce unexpected results.Parameters:
Name Type Attributes Default Description lower
number <optional>
0 The lower bound.
upper
number <optional>
1 The upper bound.
floating
boolean <optional>
Specify returning a floating-point number.
Returns:
number -Returns the random number.
- Since:
- 0.7.0
Example
_.random(0, 5); // => an integer between 0 and 5 _.random(5); // => also an integer between 0 and 5 _.random(5, true); // => a floating-point number between 0 and 5 _.random(1.2, 5.2); // => a floating-point number between 1.2 and 5.2
-
static reduce(collection, iterateeopt, accumulatoropt) → {*}
-
Reduces
collection
to a value which is the accumulated result of running
each element incollection
thruiteratee
, where each successive
invocation is supplied the return value of the previous. Ifaccumulator
is not given, the first element ofcollection
is used as the initial
value. The iteratee is invoked with four arguments:
(accumulator, value, index|key, collection).Many lodash methods are guarded to work as iteratees for methods like
_.reduce
,_.reduceRight
, and_.transform
.The guarded methods are:
assign
,defaults
,defaultsDeep
,includes
,merge
,orderBy
,
andsortBy
Parameters:
Name Type Attributes Default Description collection
Array | Object The collection to iterate over.
iteratee
function <optional>
_.identity The function invoked per iteration.
accumulator
* <optional>
The initial value.
Returns:
* -Returns the accumulated value.
- Since:
- 0.1.0
- See:
Example
_.reduce([1, 2], function(sum, n) { return sum + n; }, 0); // => 3 _.reduce({ 'a': 1, 'b': 2, 'c': 1 }, function(result, value, key) { (result[value] || (result[value] = [])).push(key); return result; }, {}); // => { '1': ['a', 'c'], '2': ['b'] } (iteration order is not guaranteed)
-
static reduceRight(collection, iterateeopt, accumulatoropt) → {*}
-
This method is like
_.reduce
except that it iterates over elements of
collection
from right to left.Parameters:
Name Type Attributes Default Description collection
Array | Object The collection to iterate over.
iteratee
function <optional>
_.identity The function invoked per iteration.
accumulator
* <optional>
The initial value.
Returns:
* -Returns the accumulated value.
- Since:
- 0.1.0
- See:
Example
var array = [[0, 1], [2, 3], [4, 5]]; _.reduceRight(array, function(flattened, other) { return flattened.concat(other); }, []); // => [4, 5, 2, 3, 0, 1]
-
static reject(collection, predicateopt) → {Array}
-
The opposite of
_.filter
; this method returns the elements ofcollection
thatpredicate
does not return truthy for.Parameters:
Name Type Attributes Default Description collection
Array | Object The collection to iterate over.
predicate
function <optional>
_.identity The function invoked per iteration.
Returns:
Array -Returns the new filtered array.
- Since:
- 0.1.0
- See:
Example
var users = [ { 'user': 'barney', 'age': 36, 'active': false }, { 'user': 'fred', 'age': 40, 'active': true } ]; _.reject(users, function(o) { return !o.active; }); // => objects for ['fred'] // The `_.matches` iteratee shorthand. _.reject(users, { 'age': 40, 'active': true }); // => objects for ['barney'] // The `_.matchesProperty` iteratee shorthand. _.reject(users, ['active', false]); // => objects for ['fred'] // The `_.property` iteratee shorthand. _.reject(users, 'active'); // => objects for ['barney']
-
static remove(array, predicateopt) → {Array}
-
Removes all elements from
array
thatpredicate
returns truthy for
and returns an array of the removed elements. The predicate is invoked
with three arguments: (value, index, array).Note: Unlike
_.filter
, this method mutatesarray
. Use_.pull
to pull elements from an array by value.Parameters:
Name Type Attributes Default Description array
Array The array to modify.
predicate
function <optional>
_.identity The function invoked per iteration.
Returns:
Array -Returns the new array of removed elements.
- Since:
- 2.0.0
Example
var array = [1, 2, 3, 4]; var evens = _.remove(array, function(n) { return n % 2 == 0; }); console.log(array); // => [1, 3] console.log(evens); // => [2, 4]
-
static repeat(stringopt, nopt) → {string}
-
Repeats the given string
n
times.Parameters:
Name Type Attributes Default Description string
string <optional>
'' The string to repeat.
n
number <optional>
1 The number of times to repeat the string.
Returns:
string -Returns the repeated string.
- Since:
- 3.0.0
Example
_.repeat('*', 3); // => '***' _.repeat('abc', 2); // => 'abcabc' _.repeat('abc', 0); // => ''
-
static replace(stringopt, pattern, replacement) → {string}
-
Replaces matches for
pattern
instring
withreplacement
.Note: This method is based on
String#replace
.Parameters:
Name Type Attributes Default Description string
string <optional>
'' The string to modify.
pattern
RegExp | string The pattern to replace.
replacement
function | string The match replacement.
Returns:
string -Returns the modified string.
- Since:
- 4.0.0
Example
_.replace('Hi Fred', 'Fred', 'Barney'); // => 'Hi Barney'
-
static rest(func, startopt) → {function}
-
Creates a function that invokes
func
with thethis
binding of the
created function and arguments fromstart
and beyond provided as
an array.Note: This method is based on the
rest parameter.Parameters:
Name Type Attributes Default Description func
function The function to apply a rest parameter to.
start
number <optional>
func.length-1 The start position of the rest parameter.
Returns:
function -Returns the new function.
- Since:
- 4.0.0
Example
var say = _.rest(function(what, names) { return what + ' ' + _.initial(names).join(', ') + (_.size(names) > 1 ? ', & ' : '') + _.last(names); }); say('hello', 'fred', 'barney', 'pebbles'); // => 'hello fred, barney, & pebbles'
-
static result(object, path, defaultValueopt) → {*}
-
This method is like
_.get
except that if the resolved value is a
function it's invoked with thethis
binding of its parent object and
its result is returned.Parameters:
Name Type Attributes Description object
Object The object to query.
path
Array | string The path of the property to resolve.
defaultValue
* <optional>
The value returned for
undefined
resolved values.Returns:
* -Returns the resolved value.
- Since:
- 0.1.0
Example
var object = { 'a': [{ 'b': { 'c1': 3, 'c2': _.constant(4) } }] }; _.result(object, 'a[0].b.c1'); // => 3 _.result(object, 'a[0].b.c2'); // => 4 _.result(object, 'a[0].b.c3', 'default'); // => 'default' _.result(object, 'a[0].b.c3', _.constant('default')); // => 'default'
-
static reverse(array) → {Array}
-
Reverses
array
so that the first element becomes the last, the second
element becomes the second to last, and so on.Note: This method mutates
array
and is based on
Array#reverse
.Parameters:
Name Type Description array
Array The array to modify.
Returns:
Array -Returns
array
.- Since:
- 4.0.0
Example
var array = [1, 2, 3]; _.reverse(array); // => [3, 2, 1] console.log(array); // => [3, 2, 1]
-
static runInContext(contextopt) → {function}
-
Create a new pristine
lodash
function using thecontext
object.Parameters:
Name Type Attributes Default Description context
Object <optional>
root The context object.
Returns:
function -Returns a new
lodash
function.- Since:
- 1.1.0
Example
_.mixin({ 'foo': _.constant('foo') }); var lodash = _.runInContext(); lodash.mixin({ 'bar': lodash.constant('bar') }); _.isFunction(_.foo); // => true _.isFunction(_.bar); // => false lodash.isFunction(lodash.foo); // => false lodash.isFunction(lodash.bar); // => true // Create a suped-up `defer` in Node.js. var defer = _.runInContext({ 'setTimeout': setImmediate }).defer;
-
static sample(collection) → {*}
-
Gets a random element from
collection
.Parameters:
Name Type Description collection
Array | Object The collection to sample.
Returns:
* -Returns the random element.
- Since:
- 2.0.0
Example
_.sample([1, 2, 3, 4]); // => 2
-
static sampleSize(collection, nopt) → {Array}
-
Gets
n
random elements at unique keys fromcollection
up to the
size ofcollection
.Parameters:
Name Type Attributes Default Description collection
Array | Object The collection to sample.
n
number <optional>
1 The number of elements to sample.
Returns:
Array -Returns the random elements.
- Since:
- 4.0.0
Example
_.sampleSize([1, 2, 3], 2); // => [3, 1] _.sampleSize([1, 2, 3], 4); // => [2, 3, 1]
-
static set(object, path, value) → {Object}
-
Sets the value at
path
ofobject
. If a portion ofpath
doesn't exist,
it's created. Arrays are created for missing index properties while objects
are created for all other missing properties. Use_.setWith
to customize
path
creation.Note: This method mutates
object
.Parameters:
Name Type Description object
Object The object to modify.
path
Array | string The path of the property to set.
value
* The value to set.
Returns:
Object -Returns
object
.- Since:
- 3.7.0
Example
var object = { 'a': [{ 'b': { 'c': 3 } }] }; _.set(object, 'a[0].b.c', 4); console.log(object.a[0].b.c); // => 4 _.set(object, ['x', '0', 'y', 'z'], 5); console.log(object.x[0].y.z); // => 5
-
static setWith(object, path, value, customizeropt) → {Object}
-
This method is like
_.set
except that it acceptscustomizer
which is
invoked to produce the objects ofpath
. Ifcustomizer
returnsundefined
path creation is handled by the method instead. Thecustomizer
is invoked
with three arguments: (nsValue, key, nsObject).Note: This method mutates
object
.Parameters:
Name Type Attributes Description object
Object The object to modify.
path
Array | string The path of the property to set.
value
* The value to set.
customizer
function <optional>
The function to customize assigned values.
Returns:
Object -Returns
object
.- Since:
- 4.0.0
Example
var object = {}; _.setWith(object, '[0][1]', 'a', Object); // => { '0': { '1': 'a' } }
-
static shuffle(collection) → {Array}
-
Creates an array of shuffled values, using a version of the
Fisher-Yates shuffle.Parameters:
Name Type Description collection
Array | Object The collection to shuffle.
Returns:
Array -Returns the new shuffled array.
- Since:
- 0.1.0
Example
_.shuffle([1, 2, 3, 4]); // => [4, 1, 3, 2]
-
static size(collection) → {number}
-
Gets the size of
collection
by returning its length for array-like
values or the number of own enumerable string keyed properties for objects.Parameters:
Name Type Description collection
Array | Object | string The collection to inspect.
Returns:
number -Returns the collection size.
- Since:
- 0.1.0
Example
_.size([1, 2, 3]); // => 3 _.size({ 'a': 1, 'b': 2 }); // => 2 _.size('pebbles'); // => 7
-
static slice(array, startopt, endopt) → {Array}
-
Creates a slice of
array
fromstart
up to, but not including,end
.Note: This method is used instead of
Array#slice
to ensure dense arrays are
returned.Parameters:
Name Type Attributes Default Description array
Array The array to slice.
start
number <optional>
0 The start position.
end
number <optional>
array.length The end position.
Returns:
Array -Returns the slice of
array
.- Since:
- 3.0.0
-
static some(collection, predicateopt) → {boolean}
-
Checks if
predicate
returns truthy for any element ofcollection
.
Iteration is stopped oncepredicate
returns truthy. The predicate is
invoked with three arguments: (value, index|key, collection).Parameters:
Name Type Attributes Default Description collection
Array | Object The collection to iterate over.
predicate
function <optional>
_.identity The function invoked per iteration.
Returns:
boolean -Returns
true
if any element passes the predicate check,
elsefalse
.- Since:
- 0.1.0
Example
_.some([null, 0, 'yes', false], Boolean); // => true var users = [ { 'user': 'barney', 'active': true }, { 'user': 'fred', 'active': false } ]; // The `_.matches` iteratee shorthand. _.some(users, { 'user': 'barney', 'active': false }); // => false // The `_.matchesProperty` iteratee shorthand. _.some(users, ['active', false]); // => true // The `_.property` iteratee shorthand. _.some(users, 'active'); // => true
-
static sortedIndex(array, value) → {number}
-
Uses a binary search to determine the lowest index at which
value
should be inserted intoarray
in order to maintain its sort order.Parameters:
Name Type Description array
Array The sorted array to inspect.
value
* The value to evaluate.
Returns:
number -Returns the index at which
value
should be inserted
intoarray
.- Since:
- 0.1.0
Example
_.sortedIndex([30, 50], 40); // => 1
-
static sortedIndexBy(array, value, iterateeopt) → {number}
-
This method is like
_.sortedIndex
except that it acceptsiteratee
which is invoked forvalue
and each element ofarray
to compute their
sort ranking. The iteratee is invoked with one argument: (value).Parameters:
Name Type Attributes Default Description array
Array The sorted array to inspect.
value
* The value to evaluate.
iteratee
function <optional>
_.identity The iteratee invoked per element.
Returns:
number -Returns the index at which
value
should be inserted
intoarray
.- Since:
- 4.0.0
Example
var objects = [{ 'x': 4 }, { 'x': 5 }]; _.sortedIndexBy(objects, { 'x': 4 }, function(o) { return o.x; }); // => 0 // The `_.property` iteratee shorthand. _.sortedIndexBy(objects, { 'x': 4 }, 'x'); // => 0
-
static sortedIndexOf(array, value) → {number}
-
This method is like
_.indexOf
except that it performs a binary
search on a sortedarray
.Parameters:
Name Type Description array
Array The array to inspect.
value
* The value to search for.
Returns:
number -Returns the index of the matched value, else
-1
.- Since:
- 4.0.0
Example
_.sortedIndexOf([4, 5, 5, 5, 6], 5); // => 1
-
static sortedLastIndex(array, value) → {number}
-
This method is like
_.sortedIndex
except that it returns the highest
index at whichvalue
should be inserted intoarray
in order to
maintain its sort order.Parameters:
Name Type Description array
Array The sorted array to inspect.
value
* The value to evaluate.
Returns:
number -Returns the index at which
value
should be inserted
intoarray
.- Since:
- 3.0.0
Example
_.sortedLastIndex([4, 5, 5, 5, 6], 5); // => 4
-
static sortedLastIndexBy(array, value, iterateeopt) → {number}
-
This method is like
_.sortedLastIndex
except that it acceptsiteratee
which is invoked forvalue
and each element ofarray
to compute their
sort ranking. The iteratee is invoked with one argument: (value).Parameters:
Name Type Attributes Default Description array
Array The sorted array to inspect.
value
* The value to evaluate.
iteratee
function <optional>
_.identity The iteratee invoked per element.
Returns:
number -Returns the index at which
value
should be inserted
intoarray
.- Since:
- 4.0.0
Example
var objects = [{ 'x': 4 }, { 'x': 5 }]; _.sortedLastIndexBy(objects, { 'x': 4 }, function(o) { return o.x; }); // => 1 // The `_.property` iteratee shorthand. _.sortedLastIndexBy(objects, { 'x': 4 }, 'x'); // => 1
-
static sortedLastIndexOf(array, value) → {number}
-
This method is like
_.lastIndexOf
except that it performs a binary
search on a sortedarray
.Parameters:
Name Type Description array
Array The array to inspect.
value
* The value to search for.
Returns:
number -Returns the index of the matched value, else
-1
.- Since:
- 4.0.0
Example
_.sortedLastIndexOf([4, 5, 5, 5, 6], 5); // => 3
-
static sortedUniq(array) → {Array}
-
This method is like
_.uniq
except that it's designed and optimized
for sorted arrays.Parameters:
Name Type Description array
Array The array to inspect.
Returns:
Array -Returns the new duplicate free array.
- Since:
- 4.0.0
Example
_.sortedUniq([1, 1, 2]); // => [1, 2]
-
static sortedUniqBy(array, iterateeopt) → {Array}
-
This method is like
_.uniqBy
except that it's designed and optimized
for sorted arrays.Parameters:
Name Type Attributes Description array
Array The array to inspect.
iteratee
function <optional>
The iteratee invoked per element.
Returns:
Array -Returns the new duplicate free array.
- Since:
- 4.0.0
Example
_.sortedUniqBy([1.1, 1.2, 2.3, 2.4], Math.floor); // => [1.1, 2.3]
-
static split(stringopt, separator, limitopt) → {Array}
-
Splits
string
byseparator
.Note: This method is based on
String#split
.Parameters:
Name Type Attributes Default Description string
string <optional>
'' The string to split.
separator
RegExp | string The separator pattern to split by.
limit
number <optional>
The length to truncate results to.
Returns:
Array -Returns the string segments.
- Since:
- 4.0.0
Example
_.split('a-b-c', '-', 2); // => ['a', 'b']
-
static spread(func, startopt) → {function}
-
Creates a function that invokes
func
with thethis
binding of the
create function and an array of arguments much like
Function#apply
.Note: This method is based on the
spread operator.Parameters:
Name Type Attributes Default Description func
function The function to spread arguments over.
start
number <optional>
0 The start position of the spread.
Returns:
function -Returns the new function.
- Since:
- 3.2.0
Example
var say = _.spread(function(who, what) { return who + ' says ' + what; }); say(['fred', 'hello']); // => 'fred says hello' var numbers = Promise.all([ Promise.resolve(40), Promise.resolve(36) ]); numbers.then(_.spread(function(x, y) { return x + y; })); // => a Promise of 76
-
static startsWith(stringopt, targetopt, positionopt) → {boolean}
-
Checks if
string
starts with the given target string.Parameters:
Name Type Attributes Default Description string
string <optional>
'' The string to inspect.
target
string <optional>
The string to search for.
position
number <optional>
0 The position to search from.
Returns:
boolean -Returns
true
ifstring
starts withtarget
,
elsefalse
.- Since:
- 3.0.0
Example
_.startsWith('abc', 'a'); // => true _.startsWith('abc', 'b'); // => false _.startsWith('abc', 'b', 1); // => true
-
static stubArray() → {Array}
-
This method returns a new empty array.
Returns:
Array -Returns the new empty array.
- Since:
- 4.13.0
Example
var arrays = _.times(2, _.stubArray); console.log(arrays); // => [[], []] console.log(arrays[0] === arrays[1]); // => false
-
static stubFalse() → {boolean}
-
This method returns
false
.Returns:
boolean -Returns
false
.- Since:
- 4.13.0
Example
_.times(2, _.stubFalse); // => [false, false]
-
static stubObject() → {Object}
-
This method returns a new empty object.
Returns:
Object -Returns the new empty object.
- Since:
- 4.13.0
Example
var objects = _.times(2, _.stubObject); console.log(objects); // => [{}, {}] console.log(objects[0] === objects[1]); // => false
-
static stubString() → {string}
-
This method returns an empty string.
Returns:
string -Returns the empty string.
- Since:
- 4.13.0
Example
_.times(2, _.stubString); // => ['', '']
-
static stubTrue() → {boolean}
-
This method returns
true
.Returns:
boolean -Returns
true
.- Since:
- 4.13.0
Example
_.times(2, _.stubTrue); // => [true, true]
-
static sum(array) → {number}
-
Computes the sum of the values in
array
.Parameters:
Name Type Description array
Array The array to iterate over.
Returns:
number -Returns the sum.
- Since:
- 3.4.0
Example
_.sum([4, 2, 8, 6]); // => 20
-
static sumBy(array, iterateeopt) → {number}
-
This method is like
_.sum
except that it acceptsiteratee
which is
invoked for each element inarray
to generate the value to be summed.
The iteratee is invoked with one argument: (value).Parameters:
Name Type Attributes Default Description array
Array The array to iterate over.
iteratee
function <optional>
_.identity The iteratee invoked per element.
Returns:
number -Returns the sum.
- Since:
- 4.0.0
Example
var objects = [{ 'n': 4 }, { 'n': 2 }, { 'n': 8 }, { 'n': 6 }]; _.sumBy(objects, function(o) { return o.n; }); // => 20 // The `_.property` iteratee shorthand. _.sumBy(objects, 'n'); // => 20
-
static tail(array) → {Array}
-
Gets all but the first element of
array
.Parameters:
Name Type Description array
Array The array to query.
Returns:
Array -Returns the slice of
array
.- Since:
- 4.0.0
Example
_.tail([1, 2, 3]); // => [2, 3]
-
static take(array, nopt) → {Array}
-
Creates a slice of
array
withn
elements taken from the beginning.Parameters:
Name Type Attributes Default Description array
Array The array to query.
n
number <optional>
1 The number of elements to take.
Returns:
Array -Returns the slice of
array
.- Since:
- 0.1.0
Example
_.take([1, 2, 3]); // => [1] _.take([1, 2, 3], 2); // => [1, 2] _.take([1, 2, 3], 5); // => [1, 2, 3] _.take([1, 2, 3], 0); // => []
-
static takeRight(array, nopt) → {Array}
-
Creates a slice of
array
withn
elements taken from the end.Parameters:
Name Type Attributes Default Description array
Array The array to query.
n
number <optional>
1 The number of elements to take.
Returns:
Array -Returns the slice of
array
.- Since:
- 3.0.0
Example
_.takeRight([1, 2, 3]); // => [3] _.takeRight([1, 2, 3], 2); // => [2, 3] _.takeRight([1, 2, 3], 5); // => [1, 2, 3] _.takeRight([1, 2, 3], 0); // => []
-
static takeRightWhile(array, predicateopt) → {Array}
-
Creates a slice of
array
with elements taken from the end. Elements are
taken untilpredicate
returns falsey. The predicate is invoked with
three arguments: (value, index, array).Parameters:
Name Type Attributes Default Description array
Array The array to query.
predicate
function <optional>
_.identity The function invoked per iteration.
Returns:
Array -Returns the slice of
array
.- Since:
- 3.0.0
Example
var users = [ { 'user': 'barney', 'active': true }, { 'user': 'fred', 'active': false }, { 'user': 'pebbles', 'active': false } ]; _.takeRightWhile(users, function(o) { return !o.active; }); // => objects for ['fred', 'pebbles'] // The `_.matches` iteratee shorthand. _.takeRightWhile(users, { 'user': 'pebbles', 'active': false }); // => objects for ['pebbles'] // The `_.matchesProperty` iteratee shorthand. _.takeRightWhile(users, ['active', false]); // => objects for ['fred', 'pebbles'] // The `_.property` iteratee shorthand. _.takeRightWhile(users, 'active'); // => []
-
static takeWhile(array, predicateopt) → {Array}
-
Creates a slice of
array
with elements taken from the beginning. Elements
are taken untilpredicate
returns falsey. The predicate is invoked with
three arguments: (value, index, array).Parameters:
Name Type Attributes Default Description array
Array The array to query.
predicate
function <optional>
_.identity The function invoked per iteration.
Returns:
Array -Returns the slice of
array
.- Since:
- 3.0.0
Example
var users = [ { 'user': 'barney', 'active': false }, { 'user': 'fred', 'active': false }, { 'user': 'pebbles', 'active': true } ]; _.takeWhile(users, function(o) { return !o.active; }); // => objects for ['barney', 'fred'] // The `_.matches` iteratee shorthand. _.takeWhile(users, { 'user': 'barney', 'active': false }); // => objects for ['barney'] // The `_.matchesProperty` iteratee shorthand. _.takeWhile(users, ['active', false]); // => objects for ['barney', 'fred'] // The `_.property` iteratee shorthand. _.takeWhile(users, 'active'); // => []
-
static tap(value, interceptor) → {*}
-
This method invokes
interceptor
and returnsvalue
. The interceptor
is invoked with one argument; (value). The purpose of this method is to
"tap into" a method chain sequence in order to modify intermediate results.Parameters:
Name Type Description value
* The value to provide to
interceptor
.interceptor
function The function to invoke.
Returns:
* -Returns
value
.- Since:
- 0.1.0
Example
_([1, 2, 3]) .tap(function(array) { // Mutate input array. array.pop(); }) .reverse() .value(); // => [2, 1]
-
static template(stringopt, optionsopt) → {function}
-
Creates a compiled template function that can interpolate data properties
in "interpolate" delimiters, HTML-escape interpolated data properties in
"escape" delimiters, and execute JavaScript in "evaluate" delimiters. Data
properties may be accessed as free variables in the template. If a setting
object is given, it takes precedence over_.templateSettings
values.Note: In the development build
_.template
utilizes
sourceURLs
for easier debugging.For more information on precompiling templates see
lodash's custom builds documentation.For more information on Chrome extension sandboxes see
Chrome's extensions documentation.Parameters:
Name Type Attributes Default Description string
string <optional>
'' The template string.
options
Object <optional>
{} The options object.
Properties
Name Type Attributes Default Description escape
RegExp <optional>
_.templateSettings.escape The HTML "escape" delimiter.
evaluate
RegExp <optional>
_.templateSettings.evaluate The "evaluate" delimiter.
imports
Object <optional>
_.templateSettings.imports An object to import into the template as free variables.
interpolate
RegExp <optional>
_.templateSettings.interpolate The "interpolate" delimiter.
sourceURL
string <optional>
'lodash.templateSources[n]' The sourceURL of the compiled template.
variable
string <optional>
'obj' The data object variable name.
Returns:
function -Returns the compiled template function.
- Since:
- 0.1.0
Example
// Use the "interpolate" delimiter to create a compiled template. var compiled = _.template('hello <%= user %>!'); compiled({ 'user': 'fred' }); // => 'hello fred!' // Use the HTML "escape" delimiter to escape data property values. var compiled = _.template('<b><%- value %></b>'); compiled({ 'value': '<script>' }); // => '<b><script></b>' // Use the "evaluate" delimiter to execute JavaScript and generate HTML. var compiled = _.template('<% _.forEach(users, function(user) { %><li><%- user %></li><% }); %>'); compiled({ 'users': ['fred', 'barney'] }); // => '<li>fred</li><li>barney</li>' // Use the internal `print` function in "evaluate" delimiters. var compiled = _.template('<% print("hello " + user); %>!'); compiled({ 'user': 'barney' }); // => 'hello barney!' // Use the ES template literal delimiter as an "interpolate" delimiter. // Disable support by replacing the "interpolate" delimiter. var compiled = _.template('hello ${ user }!'); compiled({ 'user': 'pebbles' }); // => 'hello pebbles!' // Use backslashes to treat delimiters as plain text. var compiled = _.template('<%= "\\<%- value %\\>" %>'); compiled({ 'value': 'ignored' }); // => '<%- value %>' // Use the `imports` option to import `jQuery` as `jq`. var text = '<% jq.each(users, function(user) { %><li><%- user %></li><% }); %>'; var compiled = _.template(text, { 'imports': { 'jq': jQuery } }); compiled({ 'users': ['fred', 'barney'] }); // => '<li>fred</li><li>barney</li>' // Use the `sourceURL` option to specify a custom sourceURL for the template. var compiled = _.template('hello <%= user %>!', { 'sourceURL': '/basic/greeting.jst' }); compiled(data); // => Find the source of "greeting.jst" under the Sources tab or Resources panel of the web inspector. // Use the `variable` option to ensure a with-statement isn't used in the compiled template. var compiled = _.template('hi <%= data.user %>!', { 'variable': 'data' }); compiled.source; // => function(data) { // var __t, __p = ''; // __p += 'hi ' + ((__t = ( data.user )) == null ? '' : __t) + '!'; // return __p; // } // Use custom template delimiters. _.templateSettings.interpolate = /{{([\s\S]+?)}}/g; var compiled = _.template('hello {{ user }}!'); compiled({ 'user': 'mustache' }); // => 'hello mustache!' // Use the `source` property to inline compiled templates for meaningful // line numbers in error messages and stack traces. fs.writeFileSync(path.join(process.cwd(), 'jst.js'), '\ var JST = {\ "main": ' + _.template(mainText).source + '\ };\ ');
-
static throttle(func, waitopt, optionsopt) → {function}
-
Creates a throttled function that only invokes
func
at most once per
everywait
milliseconds. The throttled function comes with acancel
method to cancel delayedfunc
invocations and aflush
method to
immediately invoke them. Provideoptions
to indicate whetherfunc
should be invoked on the leading and/or trailing edge of thewait
timeout. Thefunc
is invoked with the last arguments provided to the
throttled function. Subsequent calls to the throttled function return the
result of the lastfunc
invocation.Note: If
leading
andtrailing
options aretrue
,func
is
invoked on the trailing edge of the timeout only if the throttled function
is invoked more than once during thewait
timeout.If
wait
is0
andleading
isfalse
,func
invocation is deferred
until to the next tick, similar tosetTimeout
with a timeout of0
.See David Corbacho's article
for details over the differences between_.throttle
and_.debounce
.Parameters:
Name Type Attributes Default Description func
function The function to throttle.
wait
number <optional>
0 The number of milliseconds to throttle invocations to.
options
Object <optional>
{} The options object.
Properties
Name Type Attributes Default Description leading
boolean <optional>
true Specify invoking on the leading edge of the timeout.
trailing
boolean <optional>
true Specify invoking on the trailing edge of the timeout.
Returns:
function -Returns the new throttled function.
- Since:
- 0.1.0
Example
// Avoid excessively updating the position while scrolling. jQuery(window).on('scroll', _.throttle(updatePosition, 100)); // Invoke `renewToken` when the click event is fired, but not more than once every 5 minutes. var throttled = _.throttle(renewToken, 300000, { 'trailing': false }); jQuery(element).on('click', throttled); // Cancel the trailing throttled invocation. jQuery(window).on('popstate', throttled.cancel);
-
static thru(value, interceptor) → {*}
-
This method is like
_.tap
except that it returns the result ofinterceptor
.
The purpose of this method is to "pass thru" values replacing intermediate
results in a method chain sequence.Parameters:
Name Type Description value
* The value to provide to
interceptor
.interceptor
function The function to invoke.
Returns:
* -Returns the result of
interceptor
.- Since:
- 3.0.0
Example
_(' abc ') .chain() .trim() .thru(function(value) { return [value]; }) .value(); // => ['abc']
-
static times(n, iterateeopt) → {Array}
-
Invokes the iteratee
n
times, returning an array of the results of
each invocation. The iteratee is invoked with one argument; (index).Parameters:
Name Type Attributes Default Description n
number The number of times to invoke
iteratee
.iteratee
function <optional>
_.identity The function invoked per iteration.
Returns:
Array -Returns the array of results.
- Since:
- 0.1.0
Example
_.times(3, String); // => ['0', '1', '2'] _.times(4, _.constant(0)); // => [0, 0, 0, 0]
-
static toArray(value) → {Array}
-
Converts
value
to an array.Parameters:
Name Type Description value
* The value to convert.
Returns:
Array -Returns the converted array.
- Since:
- 0.1.0
Example
_.toArray({ 'a': 1, 'b': 2 }); // => [1, 2] _.toArray('abc'); // => ['a', 'b', 'c'] _.toArray(1); // => [] _.toArray(null); // => []
-
static toFinite(value) → {number}
-
Converts
value
to a finite number.Parameters:
Name Type Description value
* The value to convert.
Returns:
number -Returns the converted number.
- Since:
- 4.12.0
Example
_.toFinite(3.2); // => 3.2 _.toFinite(Number.MIN_VALUE); // => 5e-324 _.toFinite(Infinity); // => 1.7976931348623157e+308 _.toFinite('3.2'); // => 3.2
-
static toInteger(value) → {number}
-
Converts
value
to an integer.Note: This method is loosely based on
ToInteger
.Parameters:
Name Type Description value
* The value to convert.
Returns:
number -Returns the converted integer.
- Since:
- 4.0.0
Example
_.toInteger(3.2); // => 3 _.toInteger(Number.MIN_VALUE); // => 0 _.toInteger(Infinity); // => 1.7976931348623157e+308 _.toInteger('3.2'); // => 3
-
static toLength(value) → {number}
-
Converts
value
to an integer suitable for use as the length of an
array-like object.Note: This method is based on
ToLength
.Parameters:
Name Type Description value
* The value to convert.
Returns:
number -Returns the converted integer.
- Since:
- 4.0.0
Example
_.toLength(3.2); // => 3 _.toLength(Number.MIN_VALUE); // => 0 _.toLength(Infinity); // => 4294967295 _.toLength('3.2'); // => 3
-
static toLower(stringopt) → {string}
-
Converts
string
, as a whole, to lower case just like
String#toLowerCase.Parameters:
Name Type Attributes Default Description string
string <optional>
'' The string to convert.
Returns:
string -Returns the lower cased string.
- Since:
- 4.0.0
Example
_.toLower('--Foo-Bar--'); // => '--foo-bar--' _.toLower('fooBar'); // => 'foobar' _.toLower('__FOO_BAR__'); // => '__foo_bar__'
-
static toNumber(value) → {number}
-
Converts
value
to a number.Parameters:
Name Type Description value
* The value to process.
Returns:
number -Returns the number.
- Since:
- 4.0.0
Example
_.toNumber(3.2); // => 3.2 _.toNumber(Number.MIN_VALUE); // => 5e-324 _.toNumber(Infinity); // => Infinity _.toNumber('3.2'); // => 3.2
-
static toPath(value) → {Array}
-
Converts
value
to a property path array.Parameters:
Name Type Description value
* The value to convert.
Returns:
Array -Returns the new property path array.
- Since:
- 4.0.0
Example
_.toPath('a.b.c'); // => ['a', 'b', 'c'] _.toPath('a[0].b.c'); // => ['a', '0', 'b', 'c']
-
static toPlainObject(value) → {Object}
-
Converts
value
to a plain object flattening inherited enumerable string
keyed properties ofvalue
to own properties of the plain object.Parameters:
Name Type Description value
* The value to convert.
Returns:
Object -Returns the converted plain object.
- Since:
- 3.0.0
Example
function Foo() { this.b = 2; } Foo.prototype.c = 3; _.assign({ 'a': 1 }, new Foo); // => { 'a': 1, 'b': 2 } _.assign({ 'a': 1 }, _.toPlainObject(new Foo)); // => { 'a': 1, 'b': 2, 'c': 3 }
-
static toSafeInteger(value) → {number}
-
Converts
value
to a safe integer. A safe integer can be compared and
represented correctly.Parameters:
Name Type Description value
* The value to convert.
Returns:
number -Returns the converted integer.
- Since:
- 4.0.0
Example
_.toSafeInteger(3.2); // => 3 _.toSafeInteger(Number.MIN_VALUE); // => 0 _.toSafeInteger(Infinity); // => 9007199254740991 _.toSafeInteger('3.2'); // => 3
-
static toString(value) → {string}
-
Converts
value
to a string. An empty string is returned fornull
andundefined
values. The sign of-0
is preserved.Parameters:
Name Type Description value
* The value to convert.
Returns:
string -Returns the converted string.
- Since:
- 4.0.0
Example
_.toString(null); // => '' _.toString(-0); // => '-0' _.toString([1, 2, 3]); // => '1,2,3'
-
static toUpper(stringopt) → {string}
-
Converts
string
, as a whole, to upper case just like
String#toUpperCase.Parameters:
Name Type Attributes Default Description string
string <optional>
'' The string to convert.
Returns:
string -Returns the upper cased string.
- Since:
- 4.0.0
Example
_.toUpper('--foo-bar--'); // => '--FOO-BAR--' _.toUpper('fooBar'); // => 'FOOBAR' _.toUpper('__foo_bar__'); // => '__FOO_BAR__'
-
static transform(object, iterateeopt, accumulatoropt) → {*}
-
An alternative to
_.reduce
; this method transformsobject
to a new
accumulator
object which is the result of running each of its own
enumerable string keyed properties thruiteratee
, with each invocation
potentially mutating theaccumulator
object. Ifaccumulator
is not
provided, a new object with the same[[Prototype]]
will be used. The
iteratee is invoked with four arguments: (accumulator, value, key, object).
Iteratee functions may exit iteration early by explicitly returningfalse
.Parameters:
Name Type Attributes Default Description object
Object The object to iterate over.
iteratee
function <optional>
_.identity The function invoked per iteration.
accumulator
* <optional>
The custom accumulator value.
Returns:
* -Returns the accumulated value.
- Since:
- 1.3.0
Example
_.transform([2, 3, 4], function(result, n) { result.push(n *= n); return n % 2 == 0; }, []); // => [4, 9] _.transform({ 'a': 1, 'b': 2, 'c': 1 }, function(result, value, key) { (result[value] || (result[value] = [])).push(key); }, {}); // => { '1': ['a', 'c'], '2': ['b'] }
-
static trim(stringopt, charsopt) → {string}
-
Removes leading and trailing whitespace or specified characters from
string
.Parameters:
Name Type Attributes Default Description string
string <optional>
'' The string to trim.
chars
string <optional>
whitespace The characters to trim.
Returns:
string -Returns the trimmed string.
- Since:
- 3.0.0
Example
_.trim(' abc '); // => 'abc' _.trim('-_-abc-_-', '_-'); // => 'abc' _.map([' foo ', ' bar '], _.trim); // => ['foo', 'bar']
-
static trimEnd(stringopt, charsopt) → {string}
-
Removes trailing whitespace or specified characters from
string
.Parameters:
Name Type Attributes Default Description string
string <optional>
'' The string to trim.
chars
string <optional>
whitespace The characters to trim.
Returns:
string -Returns the trimmed string.
- Since:
- 4.0.0
Example
_.trimEnd(' abc '); // => ' abc' _.trimEnd('-_-abc-_-', '_-'); // => '-_-abc'
-
static trimStart(stringopt, charsopt) → {string}
-
Removes leading whitespace or specified characters from
string
.Parameters:
Name Type Attributes Default Description string
string <optional>
'' The string to trim.
chars
string <optional>
whitespace The characters to trim.
Returns:
string -Returns the trimmed string.
- Since:
- 4.0.0
Example
_.trimStart(' abc '); // => 'abc ' _.trimStart('-_-abc-_-', '_-'); // => 'abc-_-'
-
static truncate(stringopt, optionsopt) → {string}
-
Truncates
string
if it's longer than the given maximum string length.
The last characters of the truncated string are replaced with the omission
string which defaults to "...".Parameters:
Name Type Attributes Default Description string
string <optional>
'' The string to truncate.
options
Object <optional>
{} The options object.
Properties
Name Type Attributes Default Description length
number <optional>
30 The maximum string length.
omission
string <optional>
'...' The string to indicate text is omitted.
separator
RegExp | string <optional>
The separator pattern to truncate to.
Returns:
string -Returns the truncated string.
- Since:
- 4.0.0
Example
_.truncate('hi-diddly-ho there, neighborino'); // => 'hi-diddly-ho there, neighbo...' _.truncate('hi-diddly-ho there, neighborino', { 'length': 24, 'separator': ' ' }); // => 'hi-diddly-ho there,...' _.truncate('hi-diddly-ho there, neighborino', { 'length': 24, 'separator': /,? +/ }); // => 'hi-diddly-ho there...' _.truncate('hi-diddly-ho there, neighborino', { 'omission': ' [...]' }); // => 'hi-diddly-ho there, neig [...]'
-
static unary(func) → {function}
-
Creates a function that accepts up to one argument, ignoring any
additional arguments.Parameters:
Name Type Description func
function The function to cap arguments for.
Returns:
function -Returns the new capped function.
- Since:
- 4.0.0
Example
_.map(['6', '8', '10'], _.unary(parseInt)); // => [6, 8, 10]
-
static unescape(stringopt) → {string}
-
The inverse of
_.escape
; this method converts the HTML entities
&
,<
,>
,"
, and'
instring
to
their corresponding characters.Note: No other HTML entities are unescaped. To unescape additional
HTML entities use a third-party library like he.Parameters:
Name Type Attributes Default Description string
string <optional>
'' The string to unescape.
Returns:
string -Returns the unescaped string.
- Since:
- 0.6.0
Example
_.unescape('fred, barney, & pebbles'); // => 'fred, barney, & pebbles'
-
static uniq(array) → {Array}
-
Creates a duplicate-free version of an array, using
SameValueZero
for equality comparisons, in which only the first occurrence of each element
is kept. The order of result values is determined by the order they occur
in the array.Parameters:
Name Type Description array
Array The array to inspect.
Returns:
Array -Returns the new duplicate free array.
- Since:
- 0.1.0
Example
_.uniq([2, 1, 2]); // => [2, 1]
-
static uniqBy(array, iterateeopt) → {Array}
-
This method is like
_.uniq
except that it acceptsiteratee
which is
invoked for each element inarray
to generate the criterion by which
uniqueness is computed. The order of result values is determined by the
order they occur in the array. The iteratee is invoked with one argument:
(value).Parameters:
Name Type Attributes Default Description array
Array The array to inspect.
iteratee
function <optional>
_.identity The iteratee invoked per element.
Returns:
Array -Returns the new duplicate free array.
- Since:
- 4.0.0
Example
_.uniqBy([2.1, 1.2, 2.3], Math.floor); // => [2.1, 1.2] // The `_.property` iteratee shorthand. _.uniqBy([{ 'x': 1 }, { 'x': 2 }, { 'x': 1 }], 'x'); // => [{ 'x': 1 }, { 'x': 2 }]
-
static uniqWith(array, comparatoropt) → {Array}
-
This method is like
_.uniq
except that it acceptscomparator
which
is invoked to compare elements ofarray
. The order of result values is
determined by the order they occur in the array.The comparator is invoked
with two arguments: (arrVal, othVal).Parameters:
Name Type Attributes Description array
Array The array to inspect.
comparator
function <optional>
The comparator invoked per element.
Returns:
Array -Returns the new duplicate free array.
- Since:
- 4.0.0
Example
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }, { 'x': 1, 'y': 2 }]; _.uniqWith(objects, _.isEqual); // => [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }]
-
static uniqueId(prefixopt) → {string}
-
Generates a unique ID. If
prefix
is given, the ID is appended to it.Parameters:
Name Type Attributes Default Description prefix
string <optional>
'' The value to prefix the ID with.
Returns:
string -Returns the unique ID.
- Since:
- 0.1.0
Example
_.uniqueId('contact_'); // => 'contact_104' _.uniqueId(); // => '105'
-
static unset(object, path) → {boolean}
-
Removes the property at
path
ofobject
.Note: This method mutates
object
.Parameters:
Name Type Description object
Object The object to modify.
path
Array | string The path of the property to unset.
Returns:
boolean -Returns
true
if the property is deleted, elsefalse
.- Since:
- 4.0.0
Example
var object = { 'a': [{ 'b': { 'c': 7 } }] }; _.unset(object, 'a[0].b.c'); // => true console.log(object); // => { 'a': [{ 'b': {} }] }; _.unset(object, ['a', '0', 'b', 'c']); // => true console.log(object); // => { 'a': [{ 'b': {} }] };
-
static unzip(array) → {Array}
-
This method is like
_.zip
except that it accepts an array of grouped
elements and creates an array regrouping the elements to their pre-zip
configuration.Parameters:
Name Type Description array
Array The array of grouped elements to process.
Returns:
Array -Returns the new array of regrouped elements.
- Since:
- 1.2.0
Example
var zipped = _.zip(['a', 'b'], [1, 2], [true, false]); // => [['a', 1, true], ['b', 2, false]] _.unzip(zipped); // => [['a', 'b'], [1, 2], [true, false]]
-
static unzipWith(array, iterateeopt) → {Array}
-
This method is like
_.unzip
except that it acceptsiteratee
to specify
how regrouped values should be combined. The iteratee is invoked with the
elements of each group: (...group).Parameters:
Name Type Attributes Default Description array
Array The array of grouped elements to process.
iteratee
function <optional>
_.identity The function to combine
regrouped values.Returns:
Array -Returns the new array of regrouped elements.
- Since:
- 3.8.0
Example
var zipped = _.zip([1, 2], [10, 20], [100, 200]); // => [[1, 10, 100], [2, 20, 200]] _.unzipWith(zipped, _.add); // => [3, 30, 300]
-
static update(object, path, updater) → {Object}
-
This method is like
_.set
except that acceptsupdater
to produce the
value to set. Use_.updateWith
to customizepath
creation. Theupdater
is invoked with one argument: (value).Note: This method mutates
object
.Parameters:
Name Type Description object
Object The object to modify.
path
Array | string The path of the property to set.
updater
function The function to produce the updated value.
Returns:
Object -Returns
object
.- Since:
- 4.6.0
Example
var object = { 'a': [{ 'b': { 'c': 3 } }] }; _.update(object, 'a[0].b.c', function(n) { return n * n; }); console.log(object.a[0].b.c); // => 9 _.update(object, 'x[0].y.z', function(n) { return n ? n + 1 : 0; }); console.log(object.x[0].y.z); // => 0
-
static updateWith(object, path, updater, customizeropt) → {Object}
-
This method is like
_.update
except that it acceptscustomizer
which is
invoked to produce the objects ofpath
. Ifcustomizer
returnsundefined
path creation is handled by the method instead. Thecustomizer
is invoked
with three arguments: (nsValue, key, nsObject).Note: This method mutates
object
.Parameters:
Name Type Attributes Description object
Object The object to modify.
path
Array | string The path of the property to set.
updater
function The function to produce the updated value.
customizer
function <optional>
The function to customize assigned values.
Returns:
Object -Returns
object
.- Since:
- 4.6.0
Example
var object = {}; _.updateWith(object, '[0][1]', _.constant('a'), Object); // => { '0': { '1': 'a' } }
-
static values(object) → {Array}
-
Creates an array of the own enumerable string keyed property values of
object
.Note: Non-object values are coerced to objects.
Parameters:
Name Type Description object
Object The object to query.
Returns:
Array -Returns the array of property values.
- Since:
- 0.1.0
Example
function Foo() { this.a = 1; this.b = 2; } Foo.prototype.c = 3; _.values(new Foo); // => [1, 2] (iteration order is not guaranteed) _.values('hi'); // => ['h', 'i']
-
static valuesIn(object) → {Array}
-
Creates an array of the own and inherited enumerable string keyed property
values ofobject
.Note: Non-object values are coerced to objects.
Parameters:
Name Type Description object
Object The object to query.
Returns:
Array -Returns the array of property values.
- Since:
- 3.0.0
Example
function Foo() { this.a = 1; this.b = 2; } Foo.prototype.c = 3; _.valuesIn(new Foo); // => [1, 2, 3] (iteration order is not guaranteed)
-
static words(stringopt, patternopt) → {Array}
-
Splits
string
into an array of its words.Parameters:
Name Type Attributes Default Description string
string <optional>
'' The string to inspect.
pattern
RegExp | string <optional>
The pattern to match words.
Returns:
Array -Returns the words of
string
.- Since:
- 3.0.0
Example
_.words('fred, barney, & pebbles'); // => ['fred', 'barney', 'pebbles'] _.words('fred, barney, & pebbles', /[^, ]+/g); // => ['fred', 'barney', '&', 'pebbles']
-
static wrap(value, wrapperopt) → {function}
-
Creates a function that provides
value
towrapper
as its first
argument. Any additional arguments provided to the function are appended
to those provided to thewrapper
. The wrapper is invoked with thethis
binding of the created function.Parameters:
Name Type Attributes Default Description value
* The value to wrap.
wrapper
function <optional>
identity The wrapper function.
Returns:
function -Returns the new function.
- Since:
- 0.1.0
Example
var p = _.wrap(_.escape, function(func, text) { return '<p>' + func(text) + '</p>'; }); p('fred, barney, & pebbles'); // => '<p>fred, barney, & pebbles</p>'
-
static zipObject(propsopt, valuesopt) → {Object}
-
This method is like
_.fromPairs
except that it accepts two arrays,
one of property identifiers and one of corresponding values.Parameters:
Name Type Attributes Default Description props
Array <optional>
[] The property identifiers.
values
Array <optional>
[] The property values.
Returns:
Object -Returns the new object.
- Since:
- 0.4.0
Example
_.zipObject(['a', 'b'], [1, 2]); // => { 'a': 1, 'b': 2 }
-
static zipObjectDeep(propsopt, valuesopt) → {Object}
-
This method is like
_.zipObject
except that it supports property paths.Parameters:
Name Type Attributes Default Description props
Array <optional>
[] The property identifiers.
values
Array <optional>
[] The property values.
Returns:
Object -Returns the new object.
- Since:
- 4.1.0
Example
_.zipObjectDeep(['a.b[0].c', 'a.b[1].d'], [1, 2]); // => { 'a': { 'b': [{ 'c': 1 }, { 'd': 2 }] } }