# Lo-Dash v0.10.0
[](http://travis-ci.org/bestiejs/lodash)
A drop-in replacement[*](https://github.com/bestiejs/lodash/wiki/Drop-in-Disclaimer) 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), and [additional features](http://lodash.com/#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 build](https://raw.github.com/bestiejs/lodash/v0.10.0/lodash.js)
* [Production build](https://raw.github.com/bestiejs/lodash/v0.10.0/lodash.min.js)
* [Underscore build](https://raw.github.com/bestiejs/lodash/v0.10.0/lodash.underscore.min.js) tailored for projects already using Underscore
* CDN copies of ≤ v0.10.0’s [Production](http://cdnjs.cloudflare.com/ajax/libs/lodash.js/0.10.0/lodash.min.js), [Underscore](http://cdnjs.cloudflare.com/ajax/libs/lodash.js/0.10.0/lodash.underscore.min.js), and [Development](http://cdnjs.cloudflare.com/ajax/libs/lodash.js/0.10.0/lodash.js) builds are available on [cdnjs](http://cdnjs.com/) thanks to [CloudFlare](http://www.cloudflare.com/)
* For optimal file size, [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)
* [CascadiaJS: Lo-Dash for a better utility belt](http://www.youtube.com/watch?v=dpPy4f_SeEk)
## Features
* AMD loader support ([RequireJS](http://requirejs.org/), [curl.js](https://github.com/cujojs/curl), etc.)
* [_.bindKey](http://lodash.com/docs#bindKey) for binding [*“lazy”* defined](http://michaux.ca/articles/lazy-function-definition-pattern) methods
* [_.clone](http://lodash.com/docs#clone) supports *“deep”* cloning
* [_.contains](http://lodash.com/docs#contains) accepts a `fromIndex` argument
* [_.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
* [_.isPlainObject](http://lodash.com/docs#isPlainObject) checks if values are created by the `Object` constructor
* [_.merge](http://lodash.com/docs#merge) for a *“deep”* [_.extend](http://lodash.com/docs#extend)
* [_.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) accepts `callback` and `thisArg` arguments
* [_.template](http://lodash.com/docs#template) supports [ES6 template delimiters](http://people.mozilla.org/~jorendorff/es6-draft.html#sec-7.8.6) and utilizes [sourceURLs](http://www.html5rocks.com/en/tutorials/developertools/sourcemaps/#toc-sourceurl) for easier debugging
* [_.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, _.max, _.min, _.pluck, _.reduce, _.reduceRight, _.reject, _.shuffle, _.some, _.sortBy, _.where") accept strings
## Support
Lo-Dash has been tested in at least Chrome 5~23, Firefox 1~16, IE 6-10, Opera 9.25-12, Safari 3-6, Node.js 0.4.8-0.8.14, 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](http://dvcs.w3.org/hg/content-security-policy/raw-file/tip/csp-specification.dev.html) restrictions, may be created using the `csp` modifier argument.
The `csp` modifier is an alais of the `mobile` modifier. Chrome extensions will require [sandboxing](http://developer.chrome.com/trunk/extensions/sandboxingEval.html) or the use of either the `csp`, `mobile`, or `underscore` build.
```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, tailored for projects already using Underscore, 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.
Valid categories (case-insensitive) are *“arrays”*, *“chaining”*, *“collections”*, *“functions”*, *“objects”*, and *“utilities”*.
```bash
lodash category=collections,functions
lodash category="collections, functions"
```
* Use the `exports` argument to pass comma separated names of ways to export the `LoDash` function.
Valid exports are *“amd”*, *“commonjs”*, *“global”*, *“node”*, and *“none”*.
```bash
lodash exports=amd,commonjs,node
lodash exports="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 method/category names to include in the build.
```bash
lodash include=each,filter,map
lodash include="each, filter, map"
```
* Use the `minus` argument to pass comma separated method/category names to remove from those included in the build.
```bash
lodash underscore minus=result,shuffle
lodash underscore minus="result, shuffle"
```
* Use the `plus` argument to pass comma separated method/category names to add to those included in the build.
```bash
lodash backbone plus=random,template
lodash backbone plus="random, template"
```
* Use the `template` argument to pass the file path pattern used to match template files to precompile.
```bash
lodash template="./*.jst"
```
* Use the `settings` argument to pass the template settings used when precompiling templates.
```bash
lodash settings="{interpolate:/\\{\\{([\\s\\S]+?)\\}\\}/g}"
```
* Use the `moduleId` argument to specify the AMD module ID of Lo-Dash, which defaults to “lodash”, used by precompiled templates.
```bash
lodash moduleId="underscore"
```
All arguments, except `legacy` with `csp` or `mobile`, may be combined.
Unless specified by `-o` or `--output`, all files created are saved to the current working directory.
The following options are also supported:
* `-c`, `--stdout` Write output to standard output
* `-d`, `--debug` Write only the debug output
* `-h`, `--help` Display help information
* `-m`, `--minify` Write only the minified output
* `-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`).
## Installation and usage
In browsers:
```html
```
Using [`npm`](http://npmjs.org/):
```bash
npm install lodash
npm install -g lodash
npm link lodash
```
To avoid potential issues, update `npm` before installing Lo-Dash:
```bash
npm install npm -g
```
In [Node.js](http://nodejs.org/) and [RingoJS v0.8.0+](http://ringojs.org/):
```js
var _ = require('lodash');
```
**Note:** If Lo-Dash is installed globally, run [`npm link 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 [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
* Allow iteration of objects with a `length` property [[#799](https://github.com/documentcloud/underscore/pull/799), [test](https://github.com/bestiejs/lodash/blob/v0.10.0/test/test.js#L590-L596)]
* 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/v0.10.0/test/test.js#L603-L627)]
* 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/v0.10.0/test/test.js#L140-L146)]
* `_.isEmpty` should support jQuery/MooTools DOM query collections [[#690](https://github.com/documentcloud/underscore/pull/690), [test](https://github.com/bestiejs/lodash/blob/v0.10.0/test/test.js#L792-L797)]
* `_.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/v0.10.0/test/test.js#L873-L885)]
* `_.keys` should work with `arguments` objects cross-browser [[#396](https://github.com/documentcloud/underscore/issues/396), [test](https://github.com/bestiejs/lodash/blob/v0.10.0/test/test.js#L966-L968)]
* `_.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/v0.10.0/test/test.js#L1367-L1370)]
## Release Notes
### v0.10.0
#### Compatibility Warnings ####
* Made `_.defaults` and `_.extend` iterate only own properties of `source` objects to align with [ES6 `Object.assign`](http://people.mozilla.org/~jorendorff/es6-draft.html#sec-15.2.3.15)
* Renamed `_.lateBind` to `_.bindKey`
#### Changes ####
* Added the build commands used to custom build copyright/license headers
* Added `_.assign`
* Ensured the `underscore` build of `_.find` returns the first, not last, matched value
* Ensured `_defaults`, `_.extends`, and `_.merge` work with `_.reduce`
* Made Lo-Dash’s `npm` package installation work with more system configurations
* Made `_.extend` an alias of `_.assign`
* Optimized `_.contains`, `_.defaults`, `_.extend`, and `_.filter`
* Restricted `_.where` to iterate only own properties of the `source` object
* Updated `backbone` build Lo-Dash method dependencies
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")