lodash/README.md

# Lo-Dash v2.4.1
A utility library delivering consistency, [customization](http://lodash.com/custom-builds), [performance](http://lodash.com/benchmarks), & [extras](http://lodash.com/#features).

## Download

Check out our [wiki](https://github.com/lodash/lodash/wiki/build-differences) for details over the differences between builds.

* [Modern build](https://raw.github.com/lodash/lodash/2.4.1/dist/lodash.js) ([minified](https://raw.github.com/lodash/lodash/2.4.1/dist/lodash.min.js)) perfect for new environments<br>(Chrome ≥ 14, Firefox ≥ 10, IE ≥ 9, Node.js, Opera ≥ 12, Safari ≥ 5.1)
* [Compatibility build](https://raw.github.com/lodash/lodash/2.4.1/dist/lodash.compat.js) ([minified](https://raw.github.com/lodash/lodash/2.4.1/dist/lodash.compat.min.js)) for old environments too
* [Underscore build](https://raw.github.com/lodash/lodash/2.4.1/dist/lodash.underscore.js) ([minified](https://raw.github.com/lodash/lodash/2.4.1/dist/lodash.underscore.min.js)) as a drop-in replacement for [Underscore v1.6.0](http://underscorejs.org/#1.6.0)

CDN copies are available on [cdnjs](http://cdnjs.com/libraries/lodash.js/) & [jsDelivr](http://www.jsdelivr.com/#!lodash). For smaller file sizes, create [custom builds](http://lodash.com/custom-builds) with only the features needed.

Love modules? We’ve got you covered with [lodash-amd](https://github.com/lodash/lodash-amd/tree/2.4.1), [lodash-es6](https://github.com/lodash/lodash-es6), [lodash-node](https://npmjs.org/package/lodash-node), & [npm packages](https://npmjs.org/browse/keyword/lodash-modularized) per method.

## Dive in

There’s plenty of **[API documentation](http://lodash.com/docs)**, [unit tests](http://lodash.com/tests), & [benchmarks](http://lodash.com/benchmarks).<br>
Check out <a href="http://devdocs.io/lodash/">DevDocs</a>; a fast, organized, & searchable interface for our documentation.

The full changelog for this release is available on our [wiki](https://github.com/lodash/lodash/wiki/Changelog).<br>
A list of upcoming features is available on our [roadmap](https://github.com/lodash/lodash/wiki/Roadmap).

## Features *not* in Underscore

 * ~100% [code coverage](https://coveralls.io/r/lodash)
 * Module bundles for [AMD](https://github.com/lodash/lodash-amd/tree/2.4.1) & [Node.js](https://npmjs.org/package/lodash-node) as well as [npm packages](https://npmjs.org/browse/keyword/lodash-modularized)
 * Follows [semantic versioning](http://semver.org/) for releases
 * [_(…)](http://lodash.com/docs#_) supports intuitive chaining
 * [_.at](http://lodash.com/docs#at) for cherry-picking collection values
 * [_.bindKey](http://lodash.com/docs#bindKey) for binding [*“lazy”*](http://michaux.ca/articles/lazy-function-definition-pattern) defined methods
 * [_.clone](http://lodash.com/docs#clone) supports shallow cloning of `Date` & `RegExp` objects
 * [_.cloneDeep](http://lodash.com/docs#cloneDeep) for deep cloning arrays & objects
 * [_.contains](http://lodash.com/docs#contains) accepts a `fromIndex`
 * [_.create](http://lodash.com/docs#create) for easier object inheritance
 * [_.callback](http://lodash.com/docs#createCallback) for extending callbacks in methods & mixins
 * [_.curry](http://lodash.com/docs#curry) for creating [curried](http://hughfdjackson.com/javascript/why-curry-helps/) functions
 * [_.debounce](http://lodash.com/docs#debounce) & [_.throttle](http://lodash.com/docs#throttle) accept additional `options` for more control
 * [_.findIndex](http://lodash.com/docs#findIndex) & [_.findKey](http://lodash.com/docs#findKey) for finding indexes & keys
 * [_.forEach](http://lodash.com/docs#forEach) supports exiting early
 * [_.forIn](http://lodash.com/docs#forIn) for iterating own & inherited properties
 * [_.forOwn](http://lodash.com/docs#forOwn) for iterating own properties
 * [_.isError](http://lodash.com/docs#isError) to check for error objects
 * [_.isPlainObject](http://lodash.com/docs#isPlainObject) to check for objects created by `Object`
 * [_.keysIn](http://lodash.com/docs#keysIn) & [_.valuesIn](http://lodash.com/docs#valuesIn) for keys and values of own & inherited properties
 * [_.mapValues](http://lodash.com/docs#mapValues) for [mapping](http://lodash.com/docs#map) values to an object
 * [_.memoize](http://lodash.com/docs#memoize) exposes the `cache` of memoized functions
 * [_.merge](http://lodash.com/docs#merge) for a deep [_.extend](http://lodash.com/docs#extend)
 * [_.negate](http://lodash.com/docs#negate) to create negated predicate functions
 * [_.noop](http://lodash.com/docs#noop) for function placeholders
 * [_.parseInt](http://lodash.com/docs#parseInt) for consistent behavior
 * [_.pull](http://lodash.com/docs#pull) & [_.remove](http://lodash.com/docs#remove) for mutating arrays
 * [_.random](http://lodash.com/docs#random) supports returning floating-point numbers
 * [_.runInContext](http://lodash.com/docs#runInContext) for easier mocking
 * [_.slice](http://lodash.com/docs#slice) for creating subsets of array-like values
 * [_.sortBy](http://lodash.com/docs#sortBy) supports sorting by multiple properties
 * [_.support](http://lodash.com/docs#support) for flagging environment features
 * [_.template](http://lodash.com/docs#template) supports [*“imports”*](http://lodash.com/docs#templateSettings_imports) options & [ES6 template delimiters](http://people.mozilla.org/~jorendorff/es6-draft.html#sec-literals-string-literals)
 * [_.transform](http://lodash.com/docs#transform) as a powerful alternative to [_.reduce](http://lodash.com/docs#reduce) for transforming objects
 * [_.where](http://lodash.com/docs#where) supports deep object comparisons
 * [_.xor](http://lodash.com/docs#xor) to complement [_.difference](http://lodash.com/docs#difference), [_.intersection](http://lodash.com/docs#intersection), & [_.union](http://lodash.com/docs#union)
 * [_.zip](http://lodash.com/docs#zip) is capable of unzipping values
 * [_.bind](http://lodash.com/docs#bind), [_.curry](http://lodash.com/docs#curry), [_.partial](http://lodash.com/docs#partial), &
   [more](http://lodash.com/docs  "_.bindKey, _.partialRight") support argument placeholders
 * [_.capitalize](http://lodash.com/docs#capitalize), [_.trim](http://lodash.com/docs#trim), &
   [more](http://lodash.com/docs "_.camelCase, _.endsWith, _.escapeRegExp, _.kebabCase, _.pad, _.padLeft, _.padRight, _.repeat, _.snakeCase, _.startsWith, _.trimLeft, _.trimRight, _.truncate") string methods
 * [_.contains](http://lodash.com/docs#contains), [_.toArray](http://lodash.com/docs#toArray), &
   [more](http://lodash.com/docs "_.at, _.countBy, _.every, _.filter, _.find, _.forEach, _.forEachRight, _.groupBy, _.invoke, _.map, _.max, _.min, _.pluck, _.reduce, _.reduceRight, _.reject, _.shuffle, _.size, _.some, _.sortBy, _.where") accept strings
 * [_.dropWhile](http://lodash.com/docs#dropWhile), [_.takeWhile](http://lodash.com/docs#takeWhile), &
   [more](http://lodash.com/docs "_.drop, _.dropRightWhile, _.take, _.takeRightWhile") to complement [_.first](http://lodash.com/docs#first), [_.initial](http://lodash.com/docs#initial), [_.last](http://lodash.com/docs#last), & [_.rest](http://lodash.com/docs#rest)
 * [_.filter](http://lodash.com/docs#filter), [_.map](http://lodash.com/docs#map), &
   [more](http://lodash.com/docs "_.countBy, _.every, _.find, _.findKey, _.findLast, _.findLastIndex, _.findLastKey, _.first, _.groupBy, _.initial, _.last, _.max, _.min, _.reject, _.rest, _.some, _.sortBy, _.sortedIndex, _.uniq") support *“_.pluck”* & *“_.where”* shorthands
 * [_.findLast](http://lodash.com/docs#findLast), [_.findLastIndex](http://lodash.com/docs#findLastIndex), &
   [more](http://lodash.com/docs "_.findLastKey, _.forEachRight, _.forInRight, _.forOwnRight, _.partialRight") right-associative methods
 * [_.omit](http://lodash.com/docs#omit), [_.pick](http://lodash.com/docs#pick), &
   [more](http://lodash.com/docs "_.assign, _.clone, _.cloneDeep, _.isEqual, _.merge") accept callbacks

## Resources

 * Podcasts
  - [JavaScript Jabber](http://javascriptjabber.com/079-jsj-lo-dash-with-john-david-dalton/)

 * Posts
  - [Say “Hello” to Lo-Dash](http://kitcambridge.be/blog/say-hello-to-lo-dash/)
  - [Custom builds in Lo-Dash 2.0](http://kitcambridge.be/blog/custom-builds-in-lo-dash-2-dot-0/)

 * Videos
  - [Introduction](https://vimeo.com/44154599)
  - [Origins](https://vimeo.com/44154600)
  - [Optimizations & builds](https://vimeo.com/44154601)
  - [Native method use](https://vimeo.com/48576012)
  - [Testing](https://vimeo.com/45865290)
  - [CascadiaJS ’12](http://www.youtube.com/watch?v=dpPy4f_SeEk)

 A list of other community created podcasts, posts, & videos is available on our [wiki](https://github.com/lodash/lodash/wiki/Resources).

## Support

Tested in Chrome (19, 33-34), Firefox (3, 20, 28-29), IE 6-11, Opera (10, 12, 19-20), Safari 5-7, Node.js 0.6.21~0.10.28, Narwhal 0.3.2, PhantomJS 1.9.2, RingoJS 0.9, & Rhino 1.7RC5.

Automated browser test results [are available](https://saucelabs.com/u/lodash) as well as [Travis CI](https://travis-ci.org/) builds for [lodash](https://travis-ci.org/lodash/lodash/), [lodash-cli](https://travis-ci.org/lodash/lodash-cli/), [lodash-amd](https://travis-ci.org/lodash/lodash-amd/), [lodash-node](https://travis-ci.org/lodash/lodash-node/), & [grunt-lodash](https://travis-ci.org/lodash/grunt-lodash).

Special thanks to [Sauce Labs](https://saucelabs.com/) for providing automated browser testing.<br>
[![Sauce Labs](http://lodash.com/_img/sauce.png)](https://saucelabs.com/ "Sauce Labs: Selenium Testing & More")

## Installation & usage

In browsers:

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

Using [`npm`](http://npmjs.org/):

```bash
npm i --save lodash

{sudo} npm i -g lodash
npm ln lodash
```

In [Node.js](http://nodejs.org/) & [Ringo](http://ringojs.org/):

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

**Notes:**
 * Don’t assign values to [special variable](http://nodejs.org/api/repl.html#repl_repl_features) `_` when in the REPL
 * If Lo-Dash is installed globally, run [`npm ln lodash`](http://blog.nodejs.org/2011/03/23/npm-1-0-global-vs-local-installation/) in your project’s root directory *before* requiring it

In [Rhino](http://www.mozilla.org/rhino/):

```js
load('lodash.js');
```

In an AMD loader:

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

## Author

| [![twitter/jdalton](http://gravatar.com/avatar/299a3d891ff1920b69c364d061007043?s=70)](https://twitter.com/jdalton "Follow @jdalton on Twitter") |
|---|
| [John-David Dalton](http://allyoucanleet.com/) |

## Contributors

| [![twitter/blainebublitz](http://gravatar.com/avatar/ac1c67fd906c9fecd823ce302283b4c1?s=70)](https://twitter.com/blainebublitz "Follow @BlaineBublitz on Twitter") | [![twitter/kitcambridge](http://gravatar.com/avatar/6662a1d02f351b5ef2f8b4d815804661?s=70)](https://twitter.com/kitcambridge "Follow @kitcambridge on Twitter") | [![twitter/mathias](http://gravatar.com/avatar/24e08a9ea84deb17ae121074d0f17125?s=70)](https://twitter.com/mathias "Follow @mathias on Twitter") |
|---|---|---|
| [Blaine Bublitz](http://www.iceddev.com/) | [Kit Cambridge](http://kitcambridge.be/) | [Mathias Bynens](http://mathiasbynens.be/) |