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 v1.3.1

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

Download

• Lo-Dash builds (for modern environments):
  Development and Production

• Lo-Dash compatibility builds (for legacy and modern environments):
  Development and Production

• Underscore compatibility builds:
  Development and Production

• CDN copies of ≤ v1.3.1’s builds are available on cdnjs thanks to CloudFlare:
  Lo-Dash dev, Lo-Dash prod,
  Lo-Dash compat-dev, Lo-Dash compat-prod,
  Underscore compat-dev, and Underscore compat-prod

• For optimal file size, create a custom build with only the features you need

Dive in

We’ve got API docs, benchmarks, and unit tests.

For a list of upcoming features, check out our roadmap.

Features not in Underscore

• AMD loader support (RequireJS, curl.js, etc.)
• _(…) supports intuitive chaining
• _.at for cherry-picking collection values
• _.bindKey for binding “lazy” defined methods
• _.cloneDeep for deep cloning arrays and objects
• _.contains accepts a fromIndex argument
• _.debounce and _.throttle accept an options argument for more control
• _.createCallback to customize how callback arguments are handled and support callback shorthands in mixins
• _.findIndex and _.findKey for finding indexes and keys of collections
• _.forEach is chainable and supports exiting iteration early
• _.forIn for iterating over an object’s own and inherited properties
• _.forOwn for iterating over an object’s own properties
• _.isPlainObject checks if values are created by the Object constructor
• _.merge for a deep _.extend
• _.parseInt for consistent cross-environment behavior
• _.partial and _.partialRight for partial application without this binding
• _.runInContext for easier mocking and extended environment support
• _.support to flag environment features
• _.template supports “imports” options, ES6 template delimiters, and sourceURLs
• _.transform as a powerful alternative to _.reduce for transforming objects
• _.unzip as the inverse of _.zip
• _.where supports deep object comparisons
• _.clone, _.omit, _.pick, and more… accept callback and thisArg arguments
• _.contains, _.size, _.toArray, and more… accept strings
• _.filter, _.find, _.map, and more… support “_.pluck” and “_.where” callback shorthands

Resources

For more information check out these articles, screencasts, and other videos over Lo-Dash:

• Posts

• Say “Hello” to Lo-Dash

• Videos

• Introducing Lo-Dash
• Lo-Dash optimizations and custom builds
• Lo-Dash’s origin and why it’s a better utility belt
• Unit testing in Lo-Dash
• Lo-Dash’s approach to native method use
• CascadiaJS: Lo-Dash for a better utility belt

Support

Lo-Dash has been tested in at least Chrome 527, Firefox 221, IE 6-10, Opera 9.25~12, Safari 3-6, Node.js 0.4.8-0.10.7 (Node bug #5622 prevents 0.10.8-0.10.10 from working), Narwhal 0.3.2, PhantomJS 1.9.0, RingoJS 0.9, and Rhino 1.7RC5.

Installation and usage

In browsers:

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

Using npm:

npm install lodash

npm install -g lodash
npm link lodash

To avoid potential issues, update npm before installing Lo-Dash:

npm install npm -g

In Node.js and RingoJS ≥ v0.8.0:

var _ = require('lodash');

// or as a drop-in replacement for Underscore
var _ = require('lodash/dist/lodash.underscore');

Note: If Lo-Dash is installed globally, run npm link lodash in your project’s root directory before requiring it.

In RingoJS ≤ v0.7.0:

var _ = require('lodash')._;

In Rhino:

load('lodash.js');

In an AMD loader like RequireJS:

require({
  'paths': {
    'underscore': 'path/to/lodash'
  }
},
['underscore'], function(_) {
  console.log(_.VERSION);
});

Release Notes

^v1.3.1

• Added missing cache property to the objects returned by getObject
• Ensured maxWait unit tests pass in Ringo
• Increased the maxPoolSize value
• Optimized releaseArray and releaseObject

^v1.3.0

• Added _.transform method
• Added _.chain and _.findWhere aliases
• Added internal array and object pooling
• Added Istanbul test coverage reports to Travis CI
• Added maxWait option to _.debounce
• Added support for floating point numbers to _.random
• Added Volo configuration to package.json
• Adjusted UMD for component build
• Allowed more stable mixing of lodash and underscore build methods
• Ensured debounced function with, leading and trailing options, works as expected
• Ensured minified builds work with the Dojo builder
• Ensured minification avoids deoptimizing expressions containing boolean values
• Ensured unknown types return false in _.isObject and _.isRegExp
• Ensured _.clone, _.flatten, and _.uniq can be used as a callback for methods like _.map
• Ensured _.forIn works on objects with longer inheritance chains in IE < 9
• Ensured _.isPlainObject returns true for empty objects in IE < 9
• Ensured _.max and _.min chain correctly
• Ensured clearTimeout use doesn’t cause errors in Titanium
• Ensured that the --stdout build option doesn't write to a file
• Exposed memoized function’s cache
• Fixed Error.prototype iteration bugs
• Fixed "scripts" paths in component.json
• Made methods support customizing _.indexOf
• Made the build track dependencies of private functions
• Made the template pre-compiler build option avoid escaping non-ascii characters
• Made _.createCallback avoid binding functions if they don’t reference this
• Optimized the Closure Compiler minification process
• Optimized the large array cache for _.difference, _.intersection, and _.uniq
• Optimized internal _.flatten and _.indexOf use
• Reduced _.unzip and _.zip
• Removed special handling of arrays in _.assign and _.defaults

The full changelog is available here.

BestieJS

Lo-Dash is part of the BestieJS “Best in Class” module collection. This means we promote solid browser/environment support, ES5+ precedents, unit testing, and plenty of documentation.

Author

John-David Dalton

Contributors

Blaine Bublitz	Kit Cambridge	Mathias Bynens