lodash

A modern JavaScript utility library delivering modularity, performance, & extras.

_.assign({ 'a': 1 }, { 'b': 2 }, { 'c': 3 });
// → { 'a': 1, 'b': 2, 'c': 3 }
_.map([1, 2, 3], function(n) { return n * 3; });
// → [3, 6, 9]

The most depended on npm package with over a billion downloads!

Documentation

• API Documentation
• DevDocs – a searchable interface for our documentation

Download

Lodash is released under the MIT license & supports modern environments.
Review the build differences & pick the one that’s right for you.

• Core build (~4 kB gzipped)
• Full build (~20 kB gzipped)

Module Formats

Lodash is available in a variety of other builds & module formats.

• lodash & per method packages
• lodash-amd
• lodash-es & babel-plugin-lodash

CDN copies are available on cdnjs & jsDelivr.
Create custom builds with only the features you need.

Further Reading

• Release Notes
• Build Differences
• Changelog
• Roadmap
• More Resources

Installation

In a browser:

<script src="lodash.js"></script>

In an AMD loader:

require(['lodash'], function(_) {});

Using npm:

$ {sudo -H} npm i -g npm
$ npm i --save lodash

In Node.js:

// load the full build
var _ = require('lodash');
// load the core build
var _ = require('lodash/core');
// load the fp build for immutable auto-curried iteratee-first data-last methods
var _ = require('lodash/fp');
// or a method category

var array = require('lodash/array');
var array = require('lodash/fp/object');
// or method for smaller builds with browserify/rollup/webpack

var chunk = require('lodash/chunk');
var extend = require('lodash/fp/extend');

See the package source for more details.

Note:
Don’t assign values to the special variable “_” when in the REPL.
Install n_ for a REPL that includes lodash by default.

Features

• ~100% code coverage
• Follows semantic versioning for releases
• Lazily evaluated chaining
• _(…) supports implicit chaining
• _.ary & _.rearg to change function argument limits & order
• _.at for cherry-picking collection values
• _.attempt to execute functions which may error
• _.before to complement _.after
• _.bindKey for binding “lazy” defined methods
• _.chunk for splitting an array into chunks of a given size
• _.clone supports shallow cloning of Date & RegExp objects
• _.cloneDeep for deep cloning arrays & objects
• _.curry & _.curryRight for creating curried functions
• _.debounce & _.throttle are cancelable & accept options for more control
• _.defaultsDeep for recursively assigning default properties
• _.fill to fill arrays with values
• _.findKey for finding keys
• _.flow to complement _.flowRight (a.k.a _.compose)
• _.forEach supports exiting early
• _.forIn for iterating all enumerable properties
• _.forOwn for iterating own properties
• _.get & _.set for deep property getting & setting
• _.gt, _.gte, _.lt, & _.lte relational methods
• _.inRange for checking whether a number is within a given range
• _.isNative to check for native functions
• _.isPlainObject & _.toPlainObject to check for & convert to Object objects
• _.isTypedArray to check for typed arrays
• _.mapKeys for mapping keys to an object
• _.matches supports deep object comparisons
• _.matchesProperty to complement _.matches & _.property
• _.merge for a deep _.extend
• _.method & _.methodOf to create functions that invoke methods
• _.orderBy for sorting by multiple properties & orders
• _.overArgs for more advanced functional composition
• _.parseInt for consistent cross-environment behavior
• _.pull, _.pullAt, & _.remove for mutating arrays
• _.random supports returning floating-point numbers
• _.rest & _.spread for applying rest parameters & spreading arguments to functions
• _.runInContext for collisionless mixins & easier mocking
• _.slice for creating subsets of array-like values
• _.template supports “imports” options & ES template delimiters
• _.transform as a powerful alternative to _.reduce for transforming objects
• _.unzipWith & _.zipWith to specify how grouped values should be combined
• _.valuesIn for getting values of all enumerable properties
• _.xor to complement _.difference, _.intersection, & _.union
• _.add, _.round, _.sum, & more math methods
• _.bind, _.curry, _.partial, & more support customizable argument placeholders
• _.capitalize, _.trim, & more string methods
• _.clone, _.isEqual, & more accept customizer callbacks
• _.dropWhile, _.takeWhile, & more to complement _.first, _.initial, _.last, & _.rest
• _.findLast, _.findLastKey, & more right-associative methods
• _.includes, _.toArray, & more accept strings
• _#commit & _#plant for working with chain sequences
• _#thru to pass values thru a chain sequence

Support

Tested in Chrome 47-48, Firefox 43-44, IE 9-11, Edge 13, Safari 8-9, Node.js 0.10, 0.12, 4, & 5, & PhantomJS 1.9.8.

Automated browser & CI test runs are available.