_
_.VERSION
_.after
_.bind
_.bindAll
_.chain
_.clone
_.compact
_.compose
_.contains
_.debounce
_.defaults
_.defer
_.delay
_.difference
_.escape
_.every
_.extend
_.filter
_.find
_.first
_.flatten
_.forEach
_.functions
_.groupBy
_.has
_.identity
_.indexOf
_.initial
_.intersection
_.invoke
_.isArguments
_.isArray
_.isBoolean
_.isDate
_.isElement
_.isEmpty
_.isEqual
_.isFinite
_.isFunction
_.isNaN
_.isNull
_.isNumber
_.isObject
_.isRegExp
_.isString
_.isUndefined
_.keys
_.last
_.lastIndexOf
_.map
_.max
_.memoize
_.min
_.mixin
_.noConflict
_.once
_.partial
_.pick
_.pluck
_.range
_.reduce
_.reduceRight
_.reject
_.rest
_.result
_.shuffle
_.size
_.some
_.sortBy
_.sortedIndex
_.tap
_.template
_.throttle
_.times
_.toArray
_.union
_.uniq
_.uniqueId
_.values
_.without
_.wrap
_.zip
_.templateSettings
_.templateSettings.escape
_.templateSettings.evaluate
_.templateSettings.interpolate
_.templateSettings.variable
The lodash
function.
value
(Mixed): The value to wrap in aLoDash
instance.
(Object): Returns a LoDash
instance.
(String): The semantic version number.
Creates a new function that is restricted to executing only after it is called n
times.
n
(Number): The number of times the function must be called before it is executed.func
(Function): The function to restrict.
(Function): Returns the new restricted function.
var renderNotes = _.after(notes.length, render);
_.forEach(notes, function(note) {
note.asyncSave({ 'success': renderNotes });
});
// renderNotes is run once, after all notes have saved.
Creates a new function that, when called, invokes func
with the this
binding of thisArg
and prepends any additional bind
arguments to those passed to the bound function. Lazy defined methods may be bound by passing the object they are bound to as func
and the method name as thisArg
.
func
(Function|Object): The function to bind or the object the method belongs to.[arg1, arg2, ...]
(Mixed): Arguments to be partially applied.
(Function): Returns the new bound function.
// basic bind
var func = function(greeting) { return greeting + ': ' + this.name; };
func = _.bind(func, { 'name': 'moe' }, 'hi');
func();
// => 'hi: moe'
// lazy bind
var object = {
'name': 'moe',
'greet': function(greeting) {
return greeting + ': ' + this.name;
}
};
var func = _.bind(object, 'greet', 'hi');
func();
// => 'hi: moe'
object.greet = function(greeting) {
return greeting + ' ' + this.name + '!';
};
func();
// => 'hi moe!'
Binds methods on the object
to the object, overwriting the non-bound method. If no method names are provided, all the function properties of the object
will be bound.
object
(Object): The object to bind and assign the bound methods to.[methodName1, methodName2, ...]
(String): Method names on the object to bind.
(Object): Returns the object
.
var buttonView = {
'label': 'lodash',
'onClick': function() { alert('clicked: ' + this.label); },
'onHover': function() { console.log('hovering: ' + this.label); }
};
_.bindAll(buttonView);
jQuery('#lodash_button').on('click', buttonView.onClick);
// => When the button is clicked, `this.label` will have the correct value
Wraps the value in a lodash
chainable object.
value
(Mixed): The value to wrap.
(Object): Returns the lodash
chainable object.
var stooges = [
{ 'name': 'moe', 'age': 40 },
{ 'name': 'larry', 'age': 50 },
{ 'name': 'curly', 'age': 60 }
];
var youngest = _.chain(stooges)
.sortBy(function(stooge) { return stooge.age; })
.map(function(stooge) { return stooge.name + ' is ' + stooge.age; })
.first()
.value();
// => 'moe is 40'
Create a shallow clone of the value
. Any nested objects or arrays will be assigned by reference and not cloned.
value
(Mixed): The value to clone.
(Mixed): Returns the cloned value
.
_.clone({ 'name': 'moe' });
// => { 'name': 'moe' };
Produces a new array with all falsey values of array
removed. The values false
, null
, 0
, ""
, undefined
and NaN
are all falsey.
array
(Array): The array to compact.
(Array): Returns a new filtered array.
_.compact([0, 1, false, 2, '', 3]);
// => [1, 2, 3]
Creates a new function that is the composition of the passed functions, where each function consumes the return value of the function that follows. In math terms, composing thefunctions f()
, g()
, and h()
produces f(g(h()))
.
[func1, func2, ...]
(Function): Functions to compose.
(Function): Returns the new composed function.
var greet = function(name) { return 'hi: ' + name; };
var exclaim = function(statement) { return statement + '!'; };
var welcome = _.compose(exclaim, greet);
welcome('moe');
// => 'hi: moe!'
Checks if a given target
value is present in a collection
using strict equality for comparisons, i.e. ===
.
collection
(Array|Object): The collection to iterate over.target
(Mixed): The value to check for.
(Boolean): Returns true
if target
value is found, else false
.
_.contains([1, 2, 3], 3);
// => true
Creates a new function that will delay the execution of func
until after wait
milliseconds have elapsed since the last time it was invoked. Pass true
for immediate
to cause debounce to invoke func
on the leading, instead of the trailing, edge of the wait
timeout. Subsequent calls to the debounced function will return the result of the last func
call.
func
(Function): The function to debounce.wait
(Number): The number of milliseconds to delay.immediate
(Boolean): A flag to indicate execution is on the leading edge of the timeout.
(Function): Returns the new debounced function.
var lazyLayout = _.debounce(calculateLayout, 300);
jQuery(window).on('resize', lazyLayout);
Assigns missing properties in object
with default values from the defaults objects. As soon as a property is set, additional defaults of the same property will be ignored.
object
(Object): The object to populate.[defaults1, defaults2, ...]
(Object): The defaults objects to apply toobject
.
(Object): Returns object
.
var iceCream = { 'flavor': 'chocolate' };
_.defaults(iceCream, { 'flavor': 'vanilla', 'sprinkles': 'lots' });
// => { 'flavor': 'chocolate', 'sprinkles': 'lots' }
Defers executing the func
function until the current call stack has cleared. Additional arguments are passed to func
when it is invoked.
func
(Function): The function to defer.[arg1, arg2, ...]
(Mixed): Arguments to invoke the function with.
(Number): Returns the setTimeout
timeout id.
_.defer(function() { alert('deferred'); });
// Returns from the function before the alert runs.
Executes the func
function after wait
milliseconds. Additional arguments are passed to func
when it is invoked.
func
(Function): The function to delay.wait
(Number): The number of milliseconds to delay execution.[arg1, arg2, ...]
(Mixed): Arguments to invoke the function with.
(Number): Returns the setTimeout
timeout id.
var log = _.bind(console.log, console);
_.delay(log, 1000, 'logged later');
// => 'logged later' (Appears after one second.)
Produces a new array of array
values not present in the other arrays using strict equality for comparisons, i.e. ===
.
array
(Array): The array to process.[array1, array2, ...]
(Array): Arrays to check.
(Array): Returns a new array of array
values not present in the other arrays.
_.difference([1, 2, 3, 4, 5], [5, 2, 10]);
// => [1, 3, 4]
Escapes a string for insertion into HTML, replacing &
, <
, "
, '
, and /
characters.
string
(String): The string to escape.
(String): Returns the escaped string.
_.escape('Curly, Larry & Moe');
// => "Curly, Larry & Moe"
Checks if the callback
returns a truthy value for all elements of a collection
. The callback
is invoked with 3
arguments; for arrays they are (value, index, array) and for objects they are (value, key, object).
collection
(Array|Object): The collection to iterate over.callback
(Function): The function called per iteration.[thisArg]
(Mixed): Thethis
binding for the callback.
(Boolean): Returns true
if all values pass the callback check, else false
.
_.every([true, 1, null, 'yes'], Boolean);
// => false
Copies enumerable properties from the source objects to the destination
object. Subsequent sources will overwrite propery assignments of previous sources.
object
(Object): The destination object.[source1, source2, ...]
(Object): The source objects.
(Object): Returns the destination object.
_.extend({ 'name': 'moe' }, { 'age': 40 });
// => { 'name': 'moe', 'age': 40 }
Examines each value in a collection
, returning an array of all values the callback
returns truthy for. The callback
is invoked with 3
arguments; for arrays they are (value, index, array) and for objects they are (value, key, object).
collection
(Array|Object): The collection to iterate over.callback
(Function): The function called per iteration.[thisArg]
(Mixed): Thethis
binding for the callback.
(Array): Returns a new array of values that passed callback check.
var evens = _.filter([1, 2, 3, 4, 5, 6], function(num) { return num % 2 == 0; });
// => [2, 4, 6]
Examines each value in a collection
, returning the first one the callback
returns truthy for. The function returns as soon as it finds an acceptable value, and does not iterate over the entire collection
. The callback
is invoked with 3
arguments; for arrays they are (value, index, array) and for objects they are (value, key, object).
collection
(Array|Object): The collection to iterate over.callback
(Function): The function called per iteration.[thisArg]
(Mixed): Thethis
binding for the callback.
(Mixed): Returns the value that passed the callback check, else undefined
.
var even = _.find([1, 2, 3, 4, 5, 6], function(num) { return num % 2 == 0; });
// => 2
Gets the first value of the array
. Pass n
to return the first n
values of the array
.
array
(Array): The array to query.[n]
(Number): The number of elements to return.[guard]
(Object): Internally used to allow this method to work with others like_.map
without using their callbackindex
argument forn
.
(Mixed): Returns the first value or an array of the first n
values of the array
.
_.first([5, 4, 3, 2, 1]);
// => 5
Flattens a nested array (the nesting can be to any depth). If shallow
is truthy, array
will only be flattened a single level.
array
(Array): The array to compact.shallow
(Boolean): A flag to indicate only flattening a single level.
(Array): Returns a new flattened array.
_.flatten([1, [2], [3, [[4]]]]);
// => [1, 2, 3, 4];
_.flatten([1, [2], [3, [[4]]]], true);
// => [1, 2, 3, [[4]]];
Iterates over a collection
, executing the callback
for each value in the collection
. The callback
is bound to the thisArg
value, if one is passed. The callback
is invoked with 3
arguments; for arrays they are (value, index, array) and for objects they are (value, key, object).
collection
(Array|Object): The collection to iterate over.callback
(Function): The function called per iteration.[thisArg]
(Mixed): Thethis
binding for the callback.
(Array, Object): Returns the collection
.
_.forEach({ 'one': 1, 'two': 2, 'three': 3}, function(num) { alert(num); });
// => alerts each number in turn
_([1, 2, 3]).forEach(function(num) { alert(num); }).join(',');
// => alerts each number in turn and returns '1,2,3'
Produces a sorted array of the properties, own and inherited, of object
that have function values.
object
(Object): The object to inspect.
(Array): Returns a new array of property names that have function values.
_.functions(_);
// => ['all', 'any', 'bind', 'bindAll', 'clone', 'compact', 'compose', ...]
Splits a collection
into sets, grouped by the result of running each value through callback
. The callback
is invoked with 3
arguments; (value, index, array). The callback
argument may also be the name of a property to group by.
array
(Array): The array to iterate over.callback
(Function|String): The function called per iteration or property name to group by.[thisArg]
(Mixed): Thethis
binding for the callback.
(Object): Returns an object of grouped values.
_.groupBy([1.3, 2.1, 2.4], function(num) { return Math.floor(num); });
// => { '1': [1.3], '2': [2.1, 2.4] }
_.groupBy([1.3, 2.1, 2.4], function(num) { return this.floor(num); }, Math);
// => { '1': [1.3], '2': [2.1, 2.4] }
_.groupBy(['one', 'two', 'three'], 'length');
// => { '3': ['one', 'two'], '5': ['three'] }
Checks if the specified object property
exists and is a direct property, instead of an inherited property.
object
(Object): The object to check.property
(String): The property to check for.
(Boolean): Returns true
if key is a direct property, else false
.
_.has({ 'a': 1, 'b': 2, 'c': 3 }, 'b');
// => true
This function returns the first argument passed to it. Note: It is used throughout Lo-Dash as a default callback.
value
(Mixed): Any value.
(Mixed): Returns value
.
var moe = { 'name': 'moe' };
moe === _.identity(moe);
// => true
Gets the index at which the first occurrence of value
is found using strict equality for comparisons, i.e. ===
. If the array
is already sorted, passing true
for isSorted
will run a faster binary search.
array
(Array): The array to search.value
(Mixed): The value to search for.[isSorted=false]
(Boolean): A flag to indicate that thearray
is already sorted.
(Number): Returns the index of the matched value or -1
.
_.indexOf([1, 2, 3], 2);
// => 1
Gets all but the last value of the array
. Pass n
to exclude the last n
values from the result.
array
(Array): The array to query.[n]
(Number): The number of elements to return.[guard]
(Object): Internally used to allow this method to work with others like_.map
without using their callbackindex
argument forn
.
(Array): Returns all but the last value or n
values of the array
.
_.initial([5, 4, 3, 2, 1]);
// => [5, 4, 3, 2]
Computes the intersection of all the passed-in arrays.
[array1, array2, ...]
(Array): Arrays to process.
(Array): Returns a new array of unique values, in order, that are present in all of the arrays.
_.intersection([1, 2, 3], [101, 2, 1, 10], [2, 1]);
// => [1, 2]
Calls the method named by methodName
for each value of the collection
. Additional arguments will be passed to each invoked method.
array
(Array): The array to iterate over.methodName
(String): The name of the method to invoke.[arg1, arg2, ...]
(Mixed): Arguments to invoke the method with.
(Array): Returns a new array of values returned from each invoked method.
_.invoke([[5, 1, 7], [3, 2, 1]], 'sort');
// => [[1, 5, 7], [1, 2, 3]]
Checks if a value
is an arguments
object.
value
(Mixed): The value to check.
(Boolean): Returns true
if the value
is an arguments
object, else false
.
(function() { return _.isArguments(arguments); })(1, 2, 3);
// => true
_.isArguments([1, 2, 3]);
// => false
Checks if a value
is an array.
value
(Mixed): The value to check.
(Boolean): Returns true
if the value
is an array, else false
.
(function() { return _.isArray(arguments); })();
// => false
_.isArray([1, 2, 3]);
// => true
Checks if a value
is a boolean (true
or false
) value.
value
(Mixed): The value to check.
(Boolean): Returns true
if the value
is a boolean value, else false
.
_.isBoolean(null);
// => false
Checks if a value
is a date.
value
(Mixed): The value to check.
(Boolean): Returns true
if the value
is a date, else false
.
_.isDate(new Date);
// => true
Checks if a value
is a DOM element.
value
(Mixed): The value to check.
(Boolean): Returns true
if the value
is a DOM element, else false
.
_.isElement(document.body);
// => true
Checks if a value
is empty. Arrays or strings with a length of 0
and objects with no enumerable own properties are considered "empty".
value
(Array|Object|String): The value to inspect.
(Boolean): Returns true
if the value
is empty, else false
.
_.isEmpty([1, 2, 3]);
// => false
_.isEmpty({});
// => true
Performs a deep comparison between two values to determine if they are equivalent to each other.
a
(Mixed): The value to compare.b
(Mixed): The other value to compare.[stack]
(Array): Internally used to keep track of "seen" objects to avoid circular references.
(Boolean): Returns true
if the values are equvalent, else false
.
var moe = { 'name': 'moe', 'luckyNumbers': [13, 27, 34] };
var clone = { 'name': 'moe', 'luckyNumbers': [13, 27, 34] };
moe == clone;
// => false
_.isEqual(moe, clone);
// => true
Checks if a value
is a finite number.
value
(Mixed): The value to check.
(Boolean): Returns true
if the value
is a finite number, else false
.
_.isFinite(-101);
// => true
_.isFinite('10');
// => false
_.isFinite(Infinity);
// => false
Checks if a value
is a function.
value
(Mixed): The value to check.
(Boolean): Returns true
if the value
is a function, else false
.
_.isFunction(''.concat);
// => true
Checks if a value
is NaN
. Note: this is not the same as native isNaN
, which will return true for undefined
and other values. See http://es5.github.com/#x15.1.2.4.
value
(Mixed): The value to check.
(Boolean): Returns true
if the value
is NaN
, else false
.
_.isNaN(NaN);
// => true
_.isNaN(new Number(NaN));
// => true
isNaN(undefined);
// => true
_.isNaN(undefined);
// => false
Checks if a value
is null
.
value
(Mixed): The value to check.
(Boolean): Returns true
if the value
is null
, else false
.
_.isNull(null);
// => true
_.isNull(undefined);
// => false
Checks if a value
is a number.
value
(Mixed): The value to check.
(Boolean): Returns true
if the value
is a number, else false
.
_.isNumber(8.4 * 5;
// => true
Checks if a value
is the language type of Object. *(e.g. arrays, functions, objects, regexps, new Number(0)*
, and new String('')
)
value
(Mixed): The value to check.
(Boolean): Returns true
if the value
is an object, else false
.
_.isObject({});
// => true
_.isObject(1);
// => false
Checks if a value
is a regular expression.
value
(Mixed): The value to check.
(Boolean): Returns true
if the value
is a regular expression, else false
.
_.isRegExp(/moe/);
// => true
Checks if a value
is a string.
value
(Mixed): The value to check.
(Boolean): Returns true
if the value
is a string, else false
.
_.isString('moe');
// => true
Checks if a value
is undefined
.
value
(Mixed): The value to check.
(Boolean): Returns true
if the value
is undefined
, else false
.
_.isUndefined(void 0);
// => true
Produces an array of the object
's enumerable own property names.
object
(Object): The object to inspect.
(Array): Returns a new array of property names.
_.keys({ 'one': 1, 'two': 2, 'three': 3 });
// => ['one', 'two', 'three']
Gets the last value of the array
. Pass n
to return the lasy n
values of the array
.
array
(Array): The array to query.[n]
(Number): The number of elements to return.[guard]
(Object): Internally used to allow this method to work with others like_.map
without using their callbackindex
argument forn
.
(Array): Returns all but the last value or n
values of the array
.
_.last([5, 4, 3, 2, 1]);
// => 1
Gets the index at which the last occurrence of value
is found using strict equality for comparisons, i.e. ===
.
array
(Array): The array to search.value
(Mixed): The value to search for.
(Number): Returns the index of the matched value or -1
.
_.lastIndexOf([1, 2, 3, 1, 2, 3], 2);
// => 4
Produces a new array of values by mapping each value in the collection
through a transformation callback
. The callback
is bound to the thisArg
value, if one is passed. The callback
is invoked with 3
arguments; for arrays they are (value, index, array) and for objects they are (value, key, object).
collection
(Array|Object): The collection to iterate over.callback
(Function): The function called per iteration.[thisArg]
(Mixed): Thethis
binding for the callback.
(Array): Returns a new array of values returned by the callback.
_.map([1, 2, 3], function(num) { return num * 3; });
// => [3, 6, 9]
_.map({ 'one': 1, 'two': 2, 'three': 3 }, function(num) { return num * 3; });
// => [3, 6, 9]
Retrieves the maximum value of an array
. If callback
is passed, it will be executed for each value in the array
to generate the criterion by which the value is ranked. The callback
is invoked with 3
arguments; (value, index, array).
array
(Array): The array to iterate over.[callback]
(Function): The function called per iteration.[thisArg]
(Mixed): Thethis
binding for the callback.
(Mixed): Returns the maximum value.
var stooges = [
{ 'name': 'moe', 'age': 40 },
{ 'name': 'larry', 'age': 50 },
{ 'name': 'curly', 'age': 60 }
];
_.max(stooges, function(stooge) { return stooge.age; });
// => { 'name': 'curly', 'age': 60 };
Creates a new function that memoizes the result of func
. If resolver
is passed, it will be used to determine the cache key for storing the result based on the arguments passed to the memoized function. By default, the first argument passed to the memoized function is used as the cache key.
func
(Function): The function to have its output memoized.[resolver]
(Function): A function used to resolve the cache key.
(Function): Returns the new memoizing function.
var fibonacci = _.memoize(function(n) {
return n < 2 ? n : fibonacci(n - 1) + fibonacci(n - 2);
});
Retrieves the minimum value of an array
. If callback
is passed, it will be executed for each value in the array
to generate the criterion by which the value is ranked. The callback
is invoked with 3
arguments; (value, index, array).
array
(Array): The array to iterate over.[callback]
(Function): The function called per iteration.[thisArg]
(Mixed): Thethis
binding for the callback.
(Mixed): Returns the minimum value.
_.min([10, 5, 100, 2, 1000]);
// => 2
Adds functions properties of object
to the lodash
function and chainable wrapper.
object
(Object): The object of function properties to add tolodash
.
_.mixin({
'capitalize': function(string) {
return string.charAt(0).toUpperCase() + string.slice(1).toLowerCase();
}
});
_.capitalize('curly');
// => 'Curly'
_('larry').capitalize();
// => 'Larry'
Reverts the '_' variable to its previous value and returns a reference to the lodash
function.
(Function): Returns the lodash
function.
var lodash = _.noConflict();
Creates a new function that is restricted to one execution. Repeat calls to the function will return the value of the first call.
func
(Function): The function to restrict.
(Function): Returns the new restricted function.
var initialize = _.once(createApplication);
initialize();
initialize();
// Application is only created once.
Creates a new function that, when called, invokes func
with any additional partial
arguments prepended to those passed to the partially applied function. This method is similar bind
, except it does not alter the this
binding.
func
(Function): The function to partially apply arguments to.[arg1, arg2, ...]
(Mixed): Arguments to be partially applied.
(Function): Returns the new partially applied function.
var greet = function(greeting, name) { return greeting + ': ' + name; };
var hi = _.partial(greet, 'hi');
hi('moe');
// => 'hi: moe'
Creates an object composed of the specified properties. Property names may be specified as individual arguments or as arrays of property names.
object
(Object): The object to pluck.[prop1, prop2, ...]
(Object): The properties to pick.
(Object): Returns an object composed of the picked properties.
_.pick({ 'name': 'moe', 'age': 40, 'userid': 'moe1' }, 'name', 'age');
// => { 'name': 'moe', 'age': 40 }
Retrieves the value of a specified property from all values in a collection
.
collection
(Array|Object): The collection to iterate over.property
(String): The property to pluck.
(Array): Returns a new array of property values.
var stooges = [
{ 'name': 'moe', 'age': 40 },
{ 'name': 'larry', 'age': 50 },
{ 'name': 'curly', 'age': 60 }
];
_.pluck(stooges, 'name');
// => ['moe', 'larry', 'curly']
Creates an array of numbers (positive and/or negative) progressing from start
up to but not including stop
. This method is a port of Python's range()
function. See http://docs.python.org/library/functions.html#range.
[start=0]
(Number): The start of the range.end
(Number): The end of the range.[step=1]
(Number): The value to increment or descrement by.
(Array): Returns a new range array.
_.range(10);
// => [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
_.range(1, 11);
// => [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
_.range(0, 30, 5);
// => [0, 5, 10, 15, 20, 25]
_.range(0, -10, -1);
// => [0, -1, -2, -3, -4, -5, -6, -7, -8, -9]
_.range(0);
// => []
Boils down a collection
to a single value. The initial state of the reduction is accumulator
and each successive step of it should be returned by the callback
. The callback
is bound to the thisArg
value, if one is passed. The callback
is invoked with 4
arguments; for arrays they are (accumulator, value, index, array) and for objects they are (accumulator, value, key, object).
collection
(Array|Object): The collection to iterate over.callback
(Function): The function called per iteration.[accumulator]
(Mixed): Initial value of the accumulator.[thisArg]
(Mixed): Thethis
binding for the callback.
(Mixed): Returns the accumulated value.
var sum = _.reduce([1, 2, 3], function(memo, num) { return memo + num; });
// => 6
The right-associative version of _.reduce
. The callback
is bound to the thisArg
value, if one is passed. The callback
is invoked with 4
arguments; for arrays they are (accumulator, value, index, array) and for objects they are (accumulator, value, key, object).
collection
(Array|Object): The collection to iterate over.callback
(Function): The function called per iteration.[accumulator]
(Mixed): Initial value of the accumulator.[thisArg]
(Mixed): Thethis
binding for the callback.
(Mixed): Returns the accumulated value.
var list = [[0, 1], [2, 3], [4, 5]];
var flat = _.reduceRight(list, function(a, b) { return a.concat(b); }, []);
// => [4, 5, 2, 3, 0, 1]
The opposite of _.filter
, this method returns the values of a collection
that callback
does not return truthy for. The callback
is invoked with 3
arguments; for arrays they are (value, index, array) and for objects they are (value, key, object).
collection
(Array|Object): The collection to iterate over.callback
(Function): The function called per iteration.[thisArg]
(Mixed): Thethis
binding for the callback.
(Array): Returns a new array of values that did not pass the callback check.
var odds = _.reject([1, 2, 3, 4, 5, 6], function(num) { return num % 2 == 0; });
// => [1, 3, 5]
The opposite of _.initial
, this method gets all but the first value of the array
. Pass n
to exclude the first n
values from the result.
array
(Array): The array to query.[n]
(Number): The number of elements to return.[guard]
(Object): Internally used to allow this method to work with others like_.map
without using their callbackindex
argument forn
.
(Array): Returns all but the first value or n
values of the array
.
_.rest([5, 4, 3, 2, 1]);
// => [4, 3, 2, 1]
Resolves the value of property
on object
. If the property is a function it will be invoked and its result returned, else the property value is returned.
object
(Object): The object to inspect.property
(String): The property to get the result of.
(Mixed): Returns the resolved.
var object = {
'cheese': 'crumpets',
'stuff': function() {
return 'nonsense';
}
};
_.result(object, 'cheese');
// => 'crumpets'
_.result(object, 'stuff');
// => 'nonsense'
Produces a new array of shuffled array
values, using a version of the Fisher-Yates shuffle. See http://en.wikipedia.org/wiki/Fisher-Yates_shuffle.
array
(Array): The array to shuffle.
(Array): Returns a new shuffled array.
_.shuffle([1, 2, 3, 4, 5, 6]);
// => [4, 1, 6, 3, 5, 2]
Gets the size of a value
by returning value.length
if value
is a string or array, or the number of own enumerable properties if value
is an object.
value
(Array|Object|String): The value to inspect.
(Number): Returns value.length
if value
is a string or array, or the number of own enumerable properties if value
is an object.
_.size([1, 2]);
// => 2
_.size({ 'one': 1, 'two': 2, 'three': 3 });
// => 3
_.size('curly');
// => 5
Checks if the callback
returns a truthy value for any element of a collection
. The function returns as soon as it finds passing value, and does not iterate over the entire collection
. The callback
is invoked with 3
arguments; for arrays they are (value, index, array) and for objects they are (value, key, object).
collection
(Array|Object): The collection to iterate over.callback
(Function): The function called per iteration.[thisArg]
(Mixed): Thethis
binding for the callback.
(Boolean): Returns true
if any value passes the callback check, else false
.
_.some([null, 0, 'yes', false]);
// => true
Produces a new sorted array, ranked in ascending order by the results of running each value of a collection
through callback
. The callback
is invoked with 3
arguments; for arrays they are (value, index, array) and for objects they are (value, key, object). The callback
argument may also be the name of a property to sort by (e.g. 'length').
array
(Array): The array to iterate over.callback
(Function|String): The function called per iteration or property name to sort by.[thisArg]
(Mixed): Thethis
binding for the callback.
(Array): Returns a new array of sorted values.
_.sortBy([1, 2, 3, 4, 5, 6], function(num) { return Math.sin(num); });
// => [5, 4, 6, 3, 1, 2]
_.sortBy([1, 2, 3, 4, 5, 6], function(num) { return this.sin(num); }, Math);
// => [5, 4, 6, 3, 1, 2]
Uses a binary search to determine the smallest index at which the value
should be inserted into the collection
in order to maintain the sort order of the collection
. If callback
is passed, it will be executed for each value in the collection
to compute their sort ranking. The callback
is invoked with 1
argument; (value).
array
(Array): The array to iterate over.value
(Mixed): The value to evaluate.[callback]
(Function): The function called per iteration.
(Number): Returns the index at which the value should be inserted into the collection.
_.sortedIndex([10, 20, 30, 40, 50], 35);
// => 3
Invokes interceptor
with the value
as the first argument, and then returns value
. The primary purpose of this method is to "tap into" a method chain, in order to performoperations on intermediate results within the chain.
value
(Mixed): The value to pass tocallback
.interceptor
(Function): The function to invoke.
(Mixed): Returns value
.
_.chain([1,2,3,200])
.filter(function(num) { return num % 2 == 0; })
.tap(alert)
.map(function(num) { return num * num })
.value();
// => // [2, 200] (alerted)
// => [4, 40000]
A JavaScript micro-templating method, similar to John Resig's implementation. Lo-Dash templating handles arbitrary delimiters, preserves whitespace, and correctly escapes quotes within interpolated code.
text
(String): The template text.data
(Obect): The data object used to populate the text.options
(Object): The options object.
(Function, String): Returns a compiled function when no data
object is given, else it returns the interpolated text.
// using compiled template
var compiled = _.template('hello: <%= name %>');
compiled({ 'name': 'moe' });
// => 'hello: moe'
var list = '% _.forEach(people, function(name) { %> <li><%= name %></li> <% }); %>';
_.template(list, { 'people': ['moe', 'curly', 'larry'] });
// => '<li>moe</li><li>curly</li><li>larry</li>'
var template = _.template('<b><%- value %></b>');
template({ 'value': '<script>' });
// => '<b><script></b>'
// using `print`
var compiled = _.template('<% print("Hello " + epithet); %>');
compiled({ 'epithet': 'stooge' });
// => 'Hello stooge.'
// using custom template settings
_.templateSettings = {
'interpolate': /\{\{(.+?)\}\}/g
};
var template = _.template('Hello {{ name }}!');
template({ 'name': 'Mustache' });
// => 'Hello Mustache!'
// using the `variable` option
_.template('<%= data.hasWith %>', { 'hasWith': 'no' }, { 'variable': 'data' });
// => 'no'
// using the `source` property
<script>
JST.project = <%= _.template(jstText).source %>;
</script>
Creates a new function that, when executed, will only call the func
function at most once per every wait
milliseconds. If the throttled function is invoked more than once, func
will also be called on the trailing edge of the wait
timeout. Subsequent calls to the throttled function will return the result of the last func
call.
func
(Function): The function to throttle.wait
(Number): The number of milliseconds to throttle executions to.
(Function): Returns the new throttled function.
var throttled = _.throttle(updatePosition, 100);
jQuery(window).on('scroll', throttled);
Executes the callback
function n
times. The callback
is invoked with 1
argument; (index).
n
(Number): The number of times to execute the callback.callback
(Function): The function called per iteration.[thisArg]
(Mixed): Thethis
binding for the callback.
_.times(3, function() { genie.grantWish(); });
Converts the collection
, into an array. Useful for converting the arguments
object.
collection
(Array|Object): The collection to convert.
(Array): Returns the new converted array.
(function() { return _.toArray(arguments).slice(1); })(1, 2, 3, 4);
// => [2, 3, 4]
Computes the union of the passed-in arrays.
[array1, array2, ...]
(Array): Arrays to process.
(Array): Returns a new array of unique values, in order, that are present in one or more of the arrays.
_.union([1, 2, 3], [101, 2, 1, 10], [2, 1]);
// => [1, 2, 3, 101, 10]
Produces a duplicate-value-free version of the array
using strict equality for comparisons, i.e. ===
. If the array
is already sorted, passing true
for isSorted
will run a faster algorithm. If callback
is passed, each value of array
is passed through a transformation callback
before uniqueness is computed. The callback
is invoked with 3
arguments; (value, index, array).
array
(Array): The array to process.[isSorted=false]
(Boolean): A flag to indicate that thearray
is already sorted.[callback]
(Function): A
(Array): Returns a duplicate-value-free array.
_.uniq([1, 2, 1, 3, 1, 4]);
// => [1, 2, 3, 4]
Generates a unique id. If prefix
is passed, the id will be appended to it.
[prefix]
(String): The value to prefix the id with.
(Number, String): Returns a numeric id if no prefix is passed, else a string id may be returned.
_.uniqueId('contact_');
// => 'contact_104'
Produces an array of enumerable own property values of the collection
.
collection
(Array|Object): The collection to inspect.
(Array): Returns a new array of property values.
_.values({ 'one': 1, 'two': 2, 'three': 3 });
// => [1, 2, 3]
Produces a new array with all occurrences of the passed values removed using strict equality for comparisons, i.e. ===
.
array
(Array): The array to filter.[value1, value2, ...]
(Mixed): Values to remove.
(Array): Returns a new filtered array.
_.without([1, 2, 1, 0, 3, 1, 4], 0, 1);
// => [2, 3, 4]
Create a new function that passes the func
function to the wrapper
function as its first argument. Additional arguments are appended to those passed to the wrapper
function.
func
(Function): The function to wrap.wrapper
(Function): The wrapper function.[arg1, arg2, ...]
(Mixed): Arguments to append to those passed to the wrapper.
(Function): Returns the new function.
var hello = function(name) { return 'hello: ' + name; };
hello = _.wrap(hello, function(func) {
return 'before, ' + func('moe') + ', after';
});
hello();
// => 'before, hello: moe, after'
Merges together the values of each of the arrays with the value at the corresponding position. Useful for separate data sources that are coordinated through matching array indexes. For a matrix of nested arrays, _.zip.apply(...)
can transpose the matrix in a similar fashion.
[array1, array2, ...]
(Array): Arrays to process.
(Array): Returns a new array of merged arrays.
_.zip(['moe', 'larry', 'curly'], [30, 40, 50], [true, false, false]);
// => [['moe', 30, true], ['larry', 40, false], ['curly', 50, false]]
Extracts the value from a wrapped chainable object.
(Mixed): Returns the wrapped object.
_([1, 2, 3]).value();
// => [1, 2, 3]
Extracts the value from a wrapped chainable object.
(Mixed): Returns the wrapped object.
_([1, 2, 3]).value();
// => [1, 2, 3]
(Object): By default, Lo-Dash uses ERB-style template delimiters, change the following template settings to use alternative delimiters.
(RegExp): Used to detect data
property values to be HTML-escaped.
(RegExp): Used to detect code to be evaluated.
(RegExp): Used to detect data
property values to inject.
(String): Used to reference the data object in the template text.