# Lo-Dash v0.3.2
A drop-in replacement for Underscore.js, from the devs behind [jsPerf.com](http://jsperf.com), that delivers [performance improvements](http://lodash.com/benchmarks), [bug fixes](https://github.com/bestiejs/lodash#closed-underscorejs-issues), 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/v0.3.2/lodash.js)
* [Production source](https://raw.github.com/bestiejs/lodash/v0.3.2/lodash.min.js)
* 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).
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](http://dl.dropbox.com/u/513327/allyoucanleet/post/20/file/screencast.mp4)
* [Optimizations and custom builds](http://dl.dropbox.com/u/513327/allyoucanleet/post/21/file/screencast.mp4)
## 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
* [_.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
* [_.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
* [_.groupBy](http://lodash.com/docs#groupBy), [_.sortedIndex](http://lodash.com/docs#sortedIndex), and [_.uniq](http://lodash.com/docs#uniq) accept a `thisArg` argument
* [_.indexOf](http://lodash.com/docs#indexOf) and [_.lastIndexOf](http://lodash.com/docs#lastIndexOf) accept a `fromIndex` argument
* [_.partial](http://lodash.com/docs#partial) for more functional fun
* [_.size](http://lodash.com/docs#size) supports returning the `length` of string values
* [_.template](http://lodash.com/docs#template) utilizes [sourceURLs](http://www.html5rocks.com/en/tutorials/developertools/sourcemaps/#toc-sourceurl) for easier debugging
## Support
Lo-Dash has been tested in at least Chrome 5-19, Firefox 1.5-13, IE 6-9, Opera 9.25-12, Safari 3.0.4-5.1.3, Node.js 0.4.8-0.6.18, Narwhal 0.3.2, RingoJS 0.8, and Rhino 1.7RC3.
## Custom builds
Custom builds make it easy to create lightweight versions of Lo-Dash containing only the methods you need.
We handle all the method dependency and alias mapping for you.
* Backbone builds, containing all methods required by Backbone, may be created using the `backbone` modifier argument.
~~~ bash
node build backbone
~~~
* Mobile builds, with IE bug fixes and method compilation removed, may be created using the `mobile` modifier argument.
~~~ bash
node build mobile
~~~
Custom builds may be created in three ways:
1. Use the `category` argument to pass the categories of methods to include in the build.
Valid categories are *"arrays"*, *"chaining"*, *"collections"*, *"functions"*, *"objects"*, and *"utilities"*.
~~~ bash
node build category=collections,functions
node build category="collections, functions"
~~~
2. Use the `include` argument to pass the names of methods to include in the build.
~~~ bash
node build include=each,filter,map
node build include="each, filter, map"
~~~
3. Use the `exclude` argument to pass the names of methods to exclude from the build.
~~~ bash
node build exclude=union,uniq,zip
node build exclude="union, uniq, zip"
~~~
All arguments, except `include` and `exlcude`, may be combined.
~~~ bash
node build backbone mobile category=functions include=pick,uniq
node build backbone mobile category=utilities exclude=first,last
~~~
Custom builds are saved to `lodash.custom.js` and `lodash.custom.min.js`.
## Installation and usage
In browsers:
~~~ html
~~~
Using [npm](http://npmjs.org/):
~~~ bash
npm install lodash
~~~
In [Node.js](http://nodejs.org/) and [RingoJS v0.8.0+](http://ringojs.org/):
~~~ js
var _ = require('lodash');
~~~
In [Narwhal](http://narwhaljs.org/) and [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);
});
~~~
## Cloning this repo
To clone this repository including all submodules, using Git 1.6.5 or later:
~~~ bash
git clone --recursive https://github.com/bestiejs/lodash.git
cd lodash.js
~~~
For older Git versions, just use:
~~~ bash
git clone https://github.com/bestiejs/lodash.git
cd lodash
git submodule update --init
~~~
## Closed Underscore.js issues
* 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), [test](https://github.com/bestiejs/lodash/blob/1ba47a7c2a35552796f0c75dc2b46660e230f842/test/test.js#L271-276)]
* Ensure "Arrays" category methods allow falsey `array` arguments [[test](https://github.com/bestiejs/lodash/blob/1ba47a7c2a35552796f0c75dc2b46660e230f842/test/test.js#L758-790)]
* Ensure array-like objects with invalid `length` properties are treated like regular objects [[test](https://github.com/bestiejs/lodash/blob/1ba47a7c2a35552796f0c75dc2b46660e230f842/test/test.js#L242-248), [test](https://github.com/bestiejs/lodash/blob/1ba47a7c2a35552796f0c75dc2b46660e230f842/test/test.js#L560-569), [test](https://github.com/bestiejs/lodash/blob/1ba47a7c2a35552796f0c75dc2b46660e230f842/test/test.js#L705-708)]
* Ensure `_(…)` returns passed wrapper instances [[test](https://github.com/bestiejs/lodash/blob/801e8a5b3a963157fceaad15075690f59c22de9c/test/test.js#L106-109)]
* Ensure `_.escape` returns an empty string when passed `null` or `undefined` [[#407](https://github.com/documentcloud/underscore/issues/427), [test](https://github.com/bestiejs/lodash/blob/1ba47a7c2a35552796f0c75dc2b46660e230f842/test/test.js#L161-164)]
* Ensure `_.groupBy` adds values to own, not inherited, properties [[test](https://github.com/bestiejs/lodash/blob/1ba47a7c2a35552796f0c75dc2b46660e230f842/test/test.js#L322-329)]
* Ensure `_.sortedIndex` supports arrays with high `length` values [[test](https://github.com/bestiejs/lodash/blob/1ba47a7c2a35552796f0c75dc2b46660e230f842/test/test.js#L613-622)]
* Ensure `_.throttle` works when called in tight loops [[#502](https://github.com/documentcloud/underscore/issues/502), [test](https://github.com/bestiejs/lodash/blob/1ba47a7c2a35552796f0c75dc2b46660e230f842/test/test.js#L656-666)]
* Fix Firefox, IE, Opera, and Safari object iteration bugs [[#376](https://github.com/documentcloud/underscore/issues/376), [test](https://github.com/bestiejs/lodash/blob/1ba47a7c2a35552796f0c75dc2b46660e230f842/test/test.js#L180-192), [test](https://github.com/bestiejs/lodash/blob/1ba47a7c2a35552796f0c75dc2b46660e230f842/test/test.js#L282-307), [test](https://github.com/bestiejs/lodash/blob/1ba47a7c2a35552796f0c75dc2b46660e230f842/test/test.js#L395-406), [test](https://github.com/bestiejs/lodash/blob/1ba47a7c2a35552796f0c75dc2b46660e230f842/test/test.js#L414-416), [test](https://github.com/bestiejs/lodash/blob/1ba47a7c2a35552796f0c75dc2b46660e230f842/test/test.js#L434-454), [test](https://github.com/bestiejs/lodash/blob/1ba47a7c2a35552796f0c75dc2b46660e230f842/test/test.js#L581-583)]
* Handle arrays with `undefined` values correctly in IE < 9 [[#601](https://github.com/documentcloud/underscore/issues/601)]
* Methods should work on pages with incorrectly shimmed native methods [[#7](https://github.com/documentcloud/underscore/issues/7), [test](https://github.com/bestiejs/lodash/blob/1ba47a7c2a35552796f0c75dc2b46660e230f842/test/test.js#L88-94)]
* Register as AMD module, but still export to global [[#431](https://github.com/documentcloud/underscore/pull/431), [test](https://github.com/bestiejs/lodash/blob/1ba47a7c2a35552796f0c75dc2b46660e230f842/test/test.js#L72-86)]
* `_.forEach` should be chainable [[#142](https://github.com/documentcloud/underscore/issues/142), [test](https://github.com/bestiejs/lodash/blob/1ba47a7c2a35552796f0c75dc2b46660e230f842/test/test.js#L237-240)]
* `_isNaN(new Number(NaN))` should return `true` [[test](https://github.com/bestiejs/lodash/blob/1ba47a7c2a35552796f0c75dc2b46660e230f842/test/test.js#L424-426)]
* `_.reduceRight` should pass correct callback arguments when iterating objects [[test](https://github.com/bestiejs/lodash/blob/1ba47a7c2a35552796f0c75dc2b46660e230f842/test/test.js#L548-558)]
* `_.size` should return the `length` of string values [[test](https://github.com/bestiejs/lodash/blob/1ba47a7c2a35552796f0c75dc2b46660e230f842/test/test.js#L577-579)]
## Optimized methods (50+)
* `_.bind`
* `_.bindAll`
* `_.clone`
* `_.compact`
* `_.contains`, `_.include`
* `_.defaults`
* `_.defer`
* `_.difference`
* `_.each`
* `_.escape`
* `_.every`, `_.all`
* `_.extend`
* `_.filter`, `_.select`
* `_.find`, `_.detect`
* `_.flatten`
* `_.forEach`, `_.each`
* `_.functions`, `_.methods`
* `_.groupBy`
* `_.indexOf`
* `_.intersection`
* `_.invoke`
* `_.isEmpty`
* `_.isEqual`
* `_.isFinite`
* `_.isObject`
* `_.isString`
* `_.keys`
* `_.lastIndexOf`
* `_.map`, `_.collect`
* `_.max`
* `_.memoize`
* `_.min`
* `_.mixin`
* `_.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
### v0.3.2
* Deprecated `_(…).chain`, `_.isFinite`, `_.isNaN`, `_.isNull`, `_.isUndefined`, `_.result`, and `_.size`
* Ensured `_.escape` returns an empty string when passed `null` or `undefined`
* Ensured `sourceURL` support doesn't cause errors in Adobe's JS engine.
* Fixed regression in generating custom builds
* Moved `_.invoke` and `_.pluck` back to the *"Collections"* category
* Moved `_.tap` to the *"Chaining"* category
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/)
[](https://twitter.com/jdalton "Follow @jdalton on Twitter")
## Contributors
* [Kit Cambridge](http://kitcambridge.github.com/)
[](https://twitter.com/kitcambridge "Follow @kitcambridge on Twitter")
* [Mathias Bynens](http://mathiasbynens.be/)
[](https://twitter.com/mathias "Follow @mathias on Twitter")