lodash

What is lodash?

Lodash is a JavaScript library that provides utility functions for common programming tasks using a functional programming paradigm. It includes functions for manipulating and traversing arrays, objects, and strings, as well as utilities for functions, language, math, number, object, sequence, and utility methods.

What are lodash's main functionalities?

Array Manipulation

Lodash provides a rich set of array manipulation functions such as map, filter, find, and sort. The code sample demonstrates sorting an array in ascending order using a custom comparator.

[3, 2, 1].sort(_.compareWith(function(a, b) { return a - b; }))

Object Manipulation

Lodash allows for easy manipulation and traversal of objects. The code sample shows how to assign properties from source objects to a destination object.

_.assign({ 'a': 1 }, { 'b': 2 }, { 'c': 3 })

String Manipulation

Lodash includes functions to manipulate strings, such as converting to different cases, trimming, padding, etc. The code sample demonstrates converting a string to kebab-case.

_.kebabCase('Foo Bar')

Function Utilities

Lodash provides function utilities like debounce and throttle to control function invocation. The code sample shows a debounced function that will only be invoked after 250 milliseconds have passed without it being called again.

_.debounce(function() { console.log('Debounced'); }, 250)

Language Utilities

Lodash includes utilities for deep cloning, merging, and comparing objects. The code sample demonstrates deep cloning an object to ensure nested objects are cloned as well.

_.cloneDeep({ 'a': 1, 'b': { 'c': 2 } })

Other packages similar to lodash

underscore

Underscore is a utility library with similar functionality to Lodash, offering a range of functions for manipulating arrays, objects, and functions. It is generally considered to be the predecessor to Lodash, which provides a superset of Underscore's features with additional performance optimizations.

ramda

Ramda is a functional programming library that emphasizes a more functional and composable approach compared to Lodash. It provides similar utilities but focuses on immutability and side-effect free functions, which can lead to a different programming style.

immutable

Immutable.js offers a different take on data manipulation by providing persistent immutable data structures. Unlike Lodash, which works with standard JavaScript objects and arrays, Immutable.js uses its own data structures, which can lead to better performance and easier reasoning about state changes in certain applications.

README

Lo-Dash v2.4.0

A utility library delivering consistency, customization, performance, & extras.

Download

Check out our wiki for details over the differences between builds.

• Modern builds perfect for newer browsers/environments:
  Development & Production

• Compatibility builds for older environment support too:
  Development & Production

• Underscore builds to use as a drop-in replacement:
  Development & Production

CDN copies are available on cdnjs & jsDelivr. For smaller file sizes, create custom builds with only the features needed.

Love modules? We’ve got you covered with lodash-amd, lodash-es6, lodash-node, & npm packages per method.

Dive in

There’s plenty of documentation, unit tests, & benchmarks.
Check out DevDocs as a fast, organized, & searchable interface for our documentation.

The full changelog for this release is available on our wiki.
A list of upcoming features is available on our roadmap.

Features not in Underscore

• AMD loader support (curl, dojo, requirejs, etc.)
• _(…) supports intuitive chaining
• _.at for cherry-picking collection values
• _.bindKey for binding “lazy” defined methods
• _.clone supports shallow cloning of Date & RegExp objects
• _.cloneDeep for deep cloning arrays & objects
• _.constant & _.property function generators for composing functions
• _.contains accepts a fromIndex
• _.create for easier object inheritance
• _.createCallback for extending callbacks in methods & mixins
• _.curry for creating curried functions
• _.debounce & _.throttle accept additional options for more control
• _.findIndex & _.findKey for finding indexes & keys
• _.forEach is chainable & supports exiting early
• _.forIn for iterating own & inherited properties
• _.forOwn for iterating own properties
• _.isPlainObject for checking if values are created by Object
• _.mapValues for mapping values to an object
• _.memoize exposes the cache of memoized functions
• _.merge for a deep _.extend
• _.noop for function placeholders
• _.now as a cross-browser Date.now alternative
• _.parseInt for consistent behavior
• _.pull & _.remove for mutating arrays
• _.random supports returning floating-point numbers
• _.runInContext for easier mocking
• _.sortBy supports sorting by multiple properties
• _.support for flagging environment features
• _.template supports “imports” options & ES6 template delimiters
• _.transform as a powerful alternative to _.reduce for transforming objects
• _.where supports deep object comparisons
• _.xor as a companion to _.difference, _.intersection, & _.union
• _.zip is capable of unzipping values
• _.omit, _.pick, & more accept callbacks
• _.contains, _.toArray, & more accept strings
• _.filter, _.map, & more support “_.pluck” & “_.where” shorthands
• _.findLast, _.findLastIndex, & more right-associative methods

Resources

• Podcasts

• JavaScript Jabber

• Posts

• Say “Hello” to Lo-Dash
• Custom builds in Lo-Dash 2.0

• Videos

• Introduction
• Origins
• Optimizations & builds
• Native method use
• Testing
• CascadiaJS ’12

A list of other community created podcasts, posts, & videos is available on our wiki.

Support

Tested in Chrome 531, Firefox 225, IE 6-11, Opera 9.2517, Safari 3-7, Node.js 0.6.210.10.22, Narwhal 0.3.2, PhantomJS 1.9.2, RingoJS 0.9, & Rhino 1.7RC5.
Automated browser test results are available as well as Travis CI builds for lodash, lodash-cli, lodash-amd, lodash-node, & grunt-lodash.

Special thanks to Sauce Labs for providing automated browser testing.

Installation & usage

In browsers:

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

Using npm:

npm i --save lodash

{sudo} npm i -g lodash
npm ln lodash

In Node.js & Ringo:

var _ = require('lodash');
// or as Underscore
var _ = require('lodash/dist/lodash.underscore');

Notes:

• Don’t assign values to special variable _ when in the REPL
• If Lo-Dash is installed globally, run npm ln lodash in your project’s root directory before requiring it

In Rhino:

load('lodash.js');

In an AMD loader:

require({
  'packages': [
    { 'name': 'lodash', 'location': 'path/to/lodash', 'main': 'lodash' }
  ]
},
['lodash'], function(_) {
  console.log(_.VERSION);
});

Author

John-David Dalton

Contributors

Blaine Bublitz	Kit Cambridge	Mathias Bynens