# Lo-Dash <sup>v0.7.0</sup>

A drop-in replacement<sup>[*](https://github.com/bestiejs/lodash/wiki/Drop-in-Disclaimer)</sup> for Underscore.js, from the devs behind [jsPerf.com](http://jsperf.com), delivering [performance](http://lodash.com/benchmarks), [bug fixes](https://github.com/bestiejs/lodash#resolved-underscorejs-issues-20), and [additional features](https://github.com/bestiejs/lodash#features).

Lo-Dash’s performance is gained by avoiding slower native methods, instead opting for simplified non-ES5 compliant methods optimized for common usage, and by leveraging function compilation to reduce the number of overall function calls.

## Download

 * [Development source](https://raw.github.com/bestiejs/lodash/v0.7.0/lodash.js)
 * [Production source](https://raw.github.com/bestiejs/lodash/v0.7.0/lodash.min.js)
 * CDN copies of ≤ [v0.7.0](http://cdnjs.cloudflare.com/ajax/libs/lodash.js/0.7.0/lodash.min.js) are available on [cdnjs](http://cdnjs.com/) thanks to [CloudFlare](http://www.cloudflare.com/)
 * For optimal performance, [create a custom build](https://github.com/bestiejs/lodash#custom-builds) with only the features you need

## Dive in

We’ve got [API docs](http://lodash.com/docs), [benchmarks](http://lodash.com/benchmarks), and [unit tests](http://lodash.com/tests).

Create your own benchmarks at [jsPerf](http://jsperf.com), or [search](http://jsperf.com/search?q=lodash) for existing ones.

For a list of upcoming features, check out our [roadmap](https://github.com/bestiejs/lodash/wiki/Roadmap).

## Screencasts

For more information check out these screencasts over Lo-Dash:

 * [Introducing Lo-Dash](https://vimeo.com/44154599)
 * [Lo-Dash optimizations and custom builds](https://vimeo.com/44154601)
 * [Lo-Dash’s origin and why it’s a better utility belt](https://vimeo.com/44154600)
 * [Unit testing in Lo-Dash](https://vimeo.com/45865290)
 * [Lo-Dash’s approach to native method use](https://vimeo.com/48576012)

## Features

 * AMD loader support ([RequireJS](http://requirejs.org/), [curl.js](https://github.com/cujojs/curl), etc.)
 * [_.bind](http://lodash.com/docs#bind) supports *“lazy”* binding
 * [_.clone](http://lodash.com/docs#clone) supports *“deep”* cloning
 * [_.countBy](http://lodash.com/docs#countBy) as a companion function for [_.groupBy](http://lodash.com/docs#groupBy) and [_.sortBy](http://lodash.com/docs#sortBy)
 * [_.debounce](http://lodash.com/docs#debounce)’ed functions match [_.throttle](http://lodash.com/docs#throttle)’ed functions’ return value behavior
 * [_.forEach](http://lodash.com/docs#forEach) is chainable and supports exiting iteration early
 * [_.forIn](http://lodash.com/docs#forIn) for iterating over an object’s own and inherited properties
 * [_.forOwn](http://lodash.com/docs#forOwn) for iterating over an object’s own properties
 * [_.indexOf](http://lodash.com/docs#indexOf) and [_.lastIndexOf](http://lodash.com/docs#lastIndexOf) accept a `fromIndex` argument
 * [_.invert](http://lodash.com/docs#invert) to create inverted objects
 * [_.merge](http://lodash.com/docs#merge) for a *“deep”* [_.extend](http://lodash.com/docs#extend)
 * [_.object](http://lodash.com/docs#object) and [_.pairs](http://lodash.com/docs#pairs) for composing objects
 * [_.omit](http://lodash.com/docs#omit) for the inverse functionality of [_.pick](http://lodash.com/docs#pick)
 * [_.partial](http://lodash.com/docs#partial) for partial application without `this` binding
 * [_.pick](http://lodash.com/docs#pick) and [_.omit](http://lodash.com/docs#omit) accept `callback` and `thisArg` arguments
 * [_.random](http://lodash.com/docs#random) for generating random numbers within a given range
 * [_.sortBy](http://lodash.com/docs#sortBy) performs a [stable](http://en.wikipedia.org/wiki/Sorting_algorithm#Stability) sort
 * [_.template](http://lodash.com/docs#template) utilizes [sourceURLs](http://www.html5rocks.com/en/tutorials/developertools/sourcemaps/#toc-sourceurl) for easier debugging
 * [_.unescape](http://lodash.com/docs#unescape) to unescape strings escaped by [_.escape](http://lodash.com/docs#escape)
 * [_.where](http://lodash.com/docs#where) for filtering collections by contained properties
 * [_.countBy](http://lodash.com/docs#countBy), [_.groupBy](http://lodash.com/docs#groupBy), [_.sortedIndex](http://lodash.com/docs#sortedIndex), and [_.uniq](http://lodash.com/docs#uniq) accept a `thisArg` argument
 * [_.contains](http://lodash.com/docs#contains), [_.size](http://lodash.com/docs#size), [_.toArray](http://lodash.com/docs#toArray),
   [and more…](http://lodash.com/docs "_.countBy, _.every, _.filter, _.find, _.forEach, _.groupBy, _.invoke, _.map, _.pluck, _.reduce, _.reduceRight, _.reject, _.some, _.sortBy, _.where") accept strings

## Support

Lo-Dash has been tested in at least Chrome 5-21, Firefox 1-15, IE 6-9, Opera 9.25-12, Safari 3-6, Node.js 0.4.8-0.8.8, Narwhal 0.3.2, RingoJS 0.8, and Rhino 1.7RC5.

## Custom builds

Custom builds make it easy to create lightweight versions of Lo-Dash containing only the methods you need.
To top it off, we handle all method dependency and alias mapping for you.

 * Backbone builds, with only methods required by Backbone, may be created using the `backbone` modifier argument.
```bash
lodash backbone
```

 * CSP builds, supporting default Content Security Policy restrictions, may be created using the `csp` modifier argument.
```bash
lodash csp
```

 * Legacy builds, tailored for older browsers without [ES5 support](http://es5.github.com/), may be created using the `legacy` modifier argument.
```bash
lodash legacy
```

 * Mobile builds, with IE < 9 bug fixes and method compilation removed, may be created using the `mobile` modifier argument.
```bash
lodash mobile
```

 * Strict builds, with `_.bindAll`, `_.defaults`, and `_.extend` in [strict mode](http://es5.github.com/#C), may be created using the `strict` modifier argument.
```bash
lodash strict
```

 * Underscore builds, with iteration fixes removed and only Underscore’s API, may be created using the `underscore` modifier argument.
```bash
lodash underscore
```

Custom builds may be created using the following commands:

 * Use the `category` argument to pass comma separated categories of methods to include in the build.<br>
    Valid categories are *“arrays”*, *“chaining”*, *“collections”*, *“functions”*, *“objects”*, and *“utilities”*.
```bash
lodash category=collections,functions
lodash category="collections, functions"
```

 * Use the `exclude` argument to pass comma separated names of methods to exclude from the build.
```bash
lodash exclude=union,uniq,zip
lodash exclude="union, uniq, zip"
```

 * Use the `exports` argument to pass comma separated names of ways to export the `LoDash` function.<br>
    Valid exports are *“amd”*, *“commonjs”*, *“global”*, *“node”*, and *“none”*.
```bash
lodash exports=amd,commonjs,node
lodash include="amd, commonjs, node"
```

 * Use the `iife` argument to specify code to replace the immediately-invoked function expression that wraps Lo-Dash.
```bash
lodash iife="!function(window,undefined){%output%}(this)"
```

 * Use the `include` argument to pass comma separated names of methods to include in the build.
```bash
lodash include=each,filter,map
lodash include="each, filter, map"
```

All arguments, except `exclude` with `include` and `legacy` with `csp`/`mobile`, may be combined.

```bash
lodash backbone legacy exports=global category=utilities exclude=first,last
lodash -s underscore mobile strict exports=amd category=functions include=pick,uniq
```

The following options are also supported:

 * `-c`, `--stdout`   Write output to standard output
 * `-h`, `--help`     Display help information
 * `-o`, `--output`   Write output to a given path/filename
 * `-s`, `--silent`   Skip status updates normally logged to the console
 * `-V`, `--version`  Output current version of Lo-Dash

The `lodash` command-line utility is available when Lo-Dash is installed as a global package (i.e. `npm install -g lodash`).

Custom builds are saved to `lodash.custom.js` and `lodash.custom.min.js`.

## Installation and usage

In browsers:

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

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

```bash
npm install lodash
npm install -g lodash
```

In [Node.js](http://nodejs.org/) and [RingoJS v0.8.0+](http://ringojs.org/):

```js
var _ = require('lodash');
```

In [RingoJS v0.7.0-](http://ringojs.org/):

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

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

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

In an AMD loader like [RequireJS](http://requirejs.org/):

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

## Resolved Underscore.js issues <sup>(20+)</sup>

 * Allow iteration of objects with a `length` property [[#148](https://github.com/documentcloud/underscore/issues/148), [#154](https://github.com/documentcloud/underscore/issues/154), [#252](https://github.com/documentcloud/underscore/issues/252), [#448](https://github.com/documentcloud/underscore/issues/448), [#659](https://github.com/documentcloud/underscore/issues/659), [test](https://github.com/bestiejs/lodash/blob/v0.7.0/test/test.js#L543-549)]
 * Ensure array-like objects with invalid `length` properties are treated like regular objects [[#741](https://github.com/documentcloud/underscore/issues/741), [test](https://github.com/bestiejs/lodash/blob/v0.7.0/test/test.js#L491-501)]
 * Ensure *“Arrays”*, *“Collections”*, and *“Objects”* methods don’t error when passed falsey arguments [[#650](https://github.com/documentcloud/underscore/pull/650), [test](https://github.com/bestiejs/lodash/blob/v0.7.0/test/test.js#L1719-1754)]
 * Ensure *“Collections”* methods allow string `collection` arguments [[#247](https://github.com/documentcloud/underscore/issues/247), [#276](https://github.com/documentcloud/underscore/issues/276), [#561](https://github.com/documentcloud/underscore/pull/561), [test](https://github.com/bestiejs/lodash/blob/v0.7.0/test/test.js#L503-520)]
 * Fix cross-browser object iteration bugs [[#60](https://github.com/documentcloud/underscore/issues/60), [#376](https://github.com/documentcloud/underscore/issues/376), [test](https://github.com/bestiejs/lodash/blob/v0.7.0/test/test.js#L554-579)]
 * Methods should work on pages with incorrectly shimmed native methods [[#7](https://github.com/documentcloud/underscore/issues/7), [#742](https://github.com/documentcloud/underscore/issues/742), [test](https://github.com/bestiejs/lodash/blob/v0.7.0/test/test.js#L134-140)]
 * Register as an AMD module, but still export to global [[#431](https://github.com/documentcloud/underscore/pull/431), [test](https://github.com/bestiejs/lodash/blob/v0.7.0/test/test.js#L118-132)]
 * `_.clone` should allow `deep` cloning [[#595](https://github.com/documentcloud/underscore/pull/595), [test](https://github.com/bestiejs/lodash/blob/v0.7.0/test/test.js#L223-234)]
 * `_.contains` should work with strings [[#667](https://github.com/documentcloud/underscore/pull/667), [test](https://github.com/bestiejs/lodash/blob/v0.7.0/test/test.js#L289-298)]
 * `_.countBy` and `_.groupBy` should only add values to own, not inherited, properties [[#736](https://github.com/documentcloud/underscore/issues/736), [test](https://github.com/bestiejs/lodash/blob/v0.7.0/test/test.js#L306-313)]
 * `_.extend` should recursively extend objects [[#379](https://github.com/documentcloud/underscore/pull/379), [#718](https://github.com/documentcloud/underscore/issues/718), [test](https://github.com/bestiejs/lodash/blob/v0.7.0/test/test.js#L946-968)]
 * `_.forEach` should be chainable [[#142](https://github.com/documentcloud/underscore/issues/142), [test](https://github.com/bestiejs/lodash/blob/v0.7.0/test/test.js#L486-489)]
 * `_.forEach` should allow exiting iteration early [[#211](https://github.com/documentcloud/underscore/issues/211), [test](https://github.com/bestiejs/lodash/blob/v0.7.0/test/test.js#L581-600)]
 * `_.isElement` should use strict equality for its duck type check [[#734](https://github.com/documentcloud/underscore/issues/734), [test](https://github.com/bestiejs/lodash/blob/v0.7.0/test/test.js#L696-705)]
 * `_.isEmpty` should support jQuery/MooTools DOM query collections [[#690](https://github.com/documentcloud/underscore/pull/690), [test](https://github.com/bestiejs/lodash/blob/v0.7.0/test/test.js#L732-737)]
 * `_.isEqual` should return `true` for like-objects from different documents [[#733](https://github.com/documentcloud/underscore/issues/733), [test](https://github.com/bestiejs/lodash/blob/v0.7.0/test/test.js#L784-795)]
 * `_.isEqual` should use custom `isEqual` methods before checking strict equality [[#748](https://github.com/documentcloud/underscore/issues/748), [test](https://github.com/bestiejs/lodash/blob/v0.7.0/test/test.js#L758-761)]
 * `_.isObject` should avoid V8 bug [#2291](http://code.google.com/p/v8/issues/detail?id=2291) [[#605](https://github.com/documentcloud/underscore/issues/605), [test](https://github.com/bestiejs/lodash/blob/v0.7.0/test/test.js#L803-815)]
 * `_.isNaN(new Number(NaN))` should return `true` [[#749](https://github.com/documentcloud/underscore/issues/749), [test](https://github.com/bestiejs/lodash/blob/v0.7.0/test/test.js#L823-825)]
 * `_.keys` should work with `arguments` objects cross-browser [[#396](https://github.com/documentcloud/underscore/issues/396), [test](https://github.com/bestiejs/lodash/blob/v0.7.0/test/test.js#L879-881)]
 * `_.range` should coerce arguments to numbers [[#634](https://github.com/documentcloud/underscore/issues/634), [#683](https://github.com/documentcloud/underscore/issues/683), [test](https://github.com/bestiejs/lodash/blob/v0.7.0/test/test.js#L1222-1225)]
 * `_.reduceRight` should pass correct callback arguments when iterating objects [[test](https://github.com/bestiejs/lodash/blob/v0.7.0/test/test.js#L1257-1271)]
 * `_.sortedIndex` should support arrays with high `length` values [[#735](https://github.com/documentcloud/underscore/issues/735), [test](https://github.com/bestiejs/lodash/blob/v0.7.0/test/test.js#L1404-1413)]
 * `_.throttle` should work when called in a loop [[#502](https://github.com/documentcloud/underscore/issues/502), [test](https://github.com/bestiejs/lodash/blob/v0.7.0/test/test.js#L1534-1544)]
 * `_.toArray` uses custom `toArray` methods of arrays and strings [[#747](https://github.com/documentcloud/underscore/issues/747), [test](https://github.com/bestiejs/lodash/blob/v0.7.0/test/test.js#L1571-1579)]

## Optimized methods <sup>(50+)</sup>

 * `_.bind`
 * `_.bindAll`
 * `_.clone`
 * `_.compact`
 * `_.contains`, `_.include`
 * `_.defaults`
 * `_.defer`
 * `_.difference`
 * `_.each`
 * `_.every`, `_.all`
 * `_.extend`
 * `_.filter`, `_.select`
 * `_.find`, `_.detect`
 * `_.flatten`
 * `_.forEach`, `_.each`
 * `_.functions`, `_.methods`
 * `_.groupBy`
 * `_.indexOf`
 * `_.intersection`
 * `_.invert`
 * `_.invoke`
 * `_.isArguments`
 * `_.isDate`
 * `_.isEmpty`
 * `_.isFinite`
 * `_.isFunction`
 * `_.isObject`
 * `_.isNumber`
 * `_.isRegExp`
 * `_.isString`
 * `_.keys`
 * `_.lastIndexOf`
 * `_.map`, `_.collect`
 * `_.max`
 * `_.memoize`
 * `_.min`
 * `_.mixin`
 * `_.omit`
 * `_.pairs`
 * `_.pick`
 * `_.pluck`
 * `_.reduce`, `_.foldl`, `_.inject`
 * `_.reject`
 * `_.result`
 * `_.shuffle`
 * `_.some`, `_.any`
 * `_.sortBy`
 * `_.sortedIndex`
 * `_.template`
 * `_.throttle`
 * `_.times`
 * `_.toArray`
 * `_.union`
 * `_.uniq`, `_.unique`
 * `_.values`
 * `_.without`
 * `_.wrap`
 * `_.zip`
 * plus all `_(…)` method wrappers

## Release Notes

### <sup>v0.7.0</sup>

#### Compatibility Warnings ####

 * Renamed `_.zipObject` to `_.object`
 * Replaced `_.drop` with `_.omit`
 * Made `_.drop` alias `_.rest`

#### Changes ####

 * Added [_.invert](http://lodash.com/docs#invert), [_.pairs](http://lodash.com/docs#pairs), and [_.random](http://lodash.com/docs#random)
 * Added `_.result` to the `backbone` build
 * Added `exports`, `iife`, `-c`/`--stdout`, `-o`/`--output`, and `-s`/`--silent` build options
 * Ensured `isPlainObject` works with objects from other documements
 * Ensured `_.isEqual` compares values with circular references correctly
 * Ensured `_.merge` work with four or more arguments
 * Ensured `_.sortBy` performs a stable sort for `undefined` values
 * Ensured `_.template` works with "interpolate" delimiters containing ternary operators
 * Ensured the production build works in Node.js
 * Ensured template delimiters are tokenized correctly
 * Made pseudo private properties `_chain` and `_wrapped` double-underscored to avoid conflicts
 * Made `minify.js` support `underscore.js`
 * Reduced the size of `mobile` and `underscore` builds
 * Simplified `_.isEqual` and `_.size`

The full changelog is available [here](https://github.com/bestiejs/lodash/wiki/Changelog).

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

## Contributors

* [Kit Cambridge](http://kitcambridge.github.com/)
  [![twitter/kitcambridge](http://gravatar.com/avatar/6662a1d02f351b5ef2f8b4d815804661?s=70)](https://twitter.com/kitcambridge "Follow @kitcambridge on Twitter")
* [Mathias Bynens](http://mathiasbynens.be/)
  [![twitter/mathias](http://gravatar.com/avatar/24e08a9ea84deb17ae121074d0f17125?s=70)](https://twitter.com/mathias "Follow @mathias on Twitter")