# Lo-Dash v0.2.0
A drop-in replacement for Underscore.js, from the devs behind [jsPerf.com](http://jsperf.com), that delivers [performance improvements](http://jsperf.com/lodash-underscore#filterby=family), [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.
## Dive in
We’ve got [API docs](http://lodash.com/docs) 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
* [_.bind](http://lodash.com/docs#_bindfunc--arg1-arg2-) supports *"lazy"* binding
* [_.debounce](http://lodash.com/docs#_debouncefunc-wait-immediate)’ed functions match [_.throttle](http://lodash.com/docs#_throttlefunc-wait)’ed functions’ return value behavior
* [_.forEach](http://lodash.com/docs#_foreachcollection-callback--thisarg) is chainable
* [_.groupBy](http://lodash.com/docs#_groupbycollection-callback--thisarg) accepts a third, `thisArg`, argument
* [_.partial](http://lodash.com/docs#_partialfunc--arg1-arg2-) for more functional fun
* [_.size](http://lodash.com/docs#_sizecollection) supports returning the `length` of string values
## Support
Lo-Dash has been tested in at least Chrome 5-19, Firefox 1.5-12, IE 6-9, Opera 9.25-11.64, 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.
Custom builds may be created in two ways:
1. Use the`include` argument to pass the names of the methods to include in the build.
~~~ bash
node build include=each,filter,map,noConflict
node build include="each, filter, map, noConflict"
~~~
2. Use the `exclude` argument to pass the names of the methods to exclude from the build.
~~~ bash
node build exclude=isNaN,isUndefined,union,zip
node build exclude="isNaN, isUndefined, union, zip"
~~~
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
* Fix Firefox, IE, Opera, and Safari object iteration bugs [#376](https://github.com/documentcloud/underscore/issues/376)
* 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)
* Register as AMD module, but still export to global [#431](https://github.com/documentcloud/underscore/pull/431)
* `_.forEach` should be chainable [#142](https://github.com/documentcloud/underscore/issues/142)
* `_isNaN(new Number(NaN))` should return `true` [[test](https://github.com/bestiejs/lodash/blob/5bcd444084c92b1753feeaf66c20323e57a2dac3/test/test.js#L95-99)]
* `_.reduceRight` should pass correct callback arguments when iterating objects [[test](https://github.com/bestiejs/lodash/blob/5bcd444084c92b1753feeaf66c20323e57a2dac3/test/test.js#L106-116)]
* `_.size` should return the `length` of string values [[test](https://github.com/bestiejs/lodash/blob/5bcd444084c92b1753feeaf66c20323e57a2dac3/test/test.js#L121-127)]
## 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`, `_.intersect`
* `_.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`
* `_.toArray`
* `_.union`
* `_.uniq`, `_.unique`
* `_.values`
* `_.without`
* `_.wrap`
* `_.zip`
* plus all `_(...)` method wrappers
## Changelog
### v0.2.0
* Added custom build options
* Added default `_.templateSettings.variable` value
* Added *"lazy bind"* support to `_.bind`
* Added native method overwrite detection to avoid bad native shims
* Added support for more AMD build optimizers and aliasing as the *"underscore"* module
* Added `thisArg` argument to `_.groupBy`
* Added whitespace to compiled strings
* Added `_.partial` method
* Commented the `iterationFactory` options object
* Ensured `_.max` and `_.min` support extremely large arrays
* Fixed IE < 9 `[DontEnum]` bug and Firefox < 3.6, Opera > 9.50 - Opera < 11.60, and Safari < 5.1’s prototype property iteration bug
* Inlined `_.isFunction` calls.
* Made `_.debounce`’ed functions match `_.throttle`’ed functions’ return value behavior
* Made `_.escape` no longer translate the *">"* character
* Fixed `clearTimeout` typo
* Simplified all methods in the *"Arrays"* category
* Optimized `_.debounce`, `_.escape`, `_.flatten`, `_.forEach`, `_.groupBy`, `_.intersection`, `_.invoke`, `_.isObject`, `_.max`, `_.min`, `_.pick`, `_.shuffle`, `_.sortedIndex`, `_.template`, `_.throttle`, `_.union`, `_.uniq`
### v0.1.0
* Initial release
## 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")