A drop-in replacement for Underscore.js, from the devs behind jsPerf.com, that delivers performance improvements, bug fixes, and additional 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.
- Development source
- Production source
- Available on cdnjs thanks to CloudFlare
- For optimal performance, create a custom build with only the features you need
We’ve got API docs, benchmarks, and unit tests.
Create your own benchmarks at jsPerf, or search for existing ones.
For a list of upcoming features, check out our roadmap.
For more information check out these screencasts over Lo-Dash:
- Introducing Lo-Dash
- Optimizations and custom builds
- Lo-Dash’s origin and why it’s a better utility belt
- AMD loader support (RequireJS, curl.js, etc.)
- _.bind supports "lazy" binding
- _.debounce’ed functions match _.throttle’ed functions’ return value behavior
- _.forEach is chainable
- _.forIn for iterating over an object’s own and inherited properties
- _.forOwn for iterating over an object’s own properties
- _.groupBy, _.sortedIndex, and _.uniq accept a
thisArgargument - _.indexOf and _.lastIndexOf accept a
fromIndexargument - _.partial for more functional fun
- _.size supports returning the
lengthof string values - _.template utilizes sourceURLs for easier debugging
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 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
backbonemodifier argument.
node build backbone- Legacy builds, tailored for older browsers without ES5 support, may be created using the
legacymodifier argument.
node build legacy- Mobile builds, with IE bug fixes and method compilation remov
8000
ed, may be created using the
mobilemodifier argument.
node build mobileCustom builds may be created in three ways:
- Use the
categoryargument to pass the categories of methods to include in the build.
Valid categories are "arrays", "chaining", "collections", "functions", "objects", and "utilities".
node build category=collections,functions
node build category="collections, functions"- Use the
includeargument to pass the names of methods to include in the build.
node build include=each,filter,map
node build include="each, filter, map"- Use the
excludeargument to pass the names of methods to exclude from the build.
node build exclude=union,uniq,zip
node build exclude="union, uniq, zip"All arguments, except include with exclude and mobile with legacy, may be combined.
node build backbone mobile category=functions include=pick,uniq
node build backbone legacy category=utilities exclude=first,lastCustom builds are saved to lodash.custom.js and lodash.custom.min.js.
In browsers:
<script src="lodash.js"></script>
or use the CDN:
<script src="http://cdnjs.cloudflare.com/ajax/libs/lodash.js/0.3.2/lodash.min.js"></script>Using npm:
npm install lodashIn Node.js and RingoJS v0.8.0+:
var _ = require('lodash');In Narwhal and RingoJS v0.7.0-:
var _ = require('lodash')._;In Rhino:
load('lodash.js');In an AMD loader like RequireJS:
require({
'paths': {
'underscore': 'path/to/lodash'
}
},
['underscore'], function(_) {
console.log(_.VERSION);
});- Allow iteration of objects with a
lengthproperty [#148, #154, #252, #448, #659, test] - Ensure "Arrays" category methods allow falsey
arrayarguments [test] - Ensure array-like objects with invalid
lengthproperties are treated like regular objects [test, test, test] - Ensure
_(…)returns passed wrapper instances [test] - Ensure
_.escapereturns an empty string when passednullorundefined[#407, test] - Ensure
_.groupByadds values to own, not inherited, properties [test] - Ensure
_.sortedIndexsupports arrays with highlengthvalues [test] - Ensure
_.throttleworks when called in tight loops [#502, test] - Fix Firefox, IE, Opera, and Safari object iteration bugs [#376, test, test, test, test, test, test]
- Handle arrays with
undefinedvalues correctly in IE < 9 [#601] - Methods should work on pages with incorrectly shimmed native methods [#7, test]
- Register as AMD module, but still export to global [#431, test]
_.forEachshould be chainable [#142, test]_isNaN(new Number(NaN))should returntrue[test]_.reduceRightshould pass correct callback arguments when iterating objects [test]_.sizeshould return thelengthof string values [test]
_.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_.isArguments_.isDate_.isEmpty_.isEqual_.isFinite_.isFunction_.isObject_.isNumber_.isRegExp_.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
- Deprecated
_(…).chain,_.isFinite,_.isNaN,_.isNull,_.isUndefined,_.result, and_.size - Ensured
_.escapereturns an empty string when passednullorundefined - Ensured
sourceURLsupport doesn't cause errors in Adobe's JS engine. - Fixed regression in generating custom builds
- Moved
_.invokeand_.pluckback to the "Collections" category - Moved
_.tapto the "Chaining" category
The full changelog is available here.
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.
