A drop-in replacement* for Underscore.js, from the devs behind jsPerf.com, delivering performance, 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
- CDN copies of ≤ v0.7.0 are 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
- Lo-Dash optimizations and custom builds
- Lo-Dash’s origin and why it’s a better utility belt
- Unit testing in Lo-Dash
- Lo-Dash’s approach to native method use
- AMD loader support (RequireJS, curl.js, etc.)
- _.clone supports “deep” cloning
- _.countBy as a companion function for _.groupBy and _.sortBy
- _.debounce’ed functions match _.throttle’ed functions’ return value behavior
- _.forEach is chainable and supports exiting iteration early
- _.forIn for iterating over an object’s own and inherited properties
- _.forOwn for iterating over an object’s own properties
- _.indexOf and _.lastIndexOf accept a
fromIndex
argument - _.invert to create inverted objects
- _.merge for a “deep” _.extend
- _.object and _.pairs for composing objects
- _.omit for the inverse functionality of _.pick
- _.partial for partial application without
this
binding - _.pick and _.omit accept
callback
andthisArg
arguments - _.random for generating random numbers within a given range
- _.sortBy performs a stable sort
- _.template utilizes sourceURLs for easier debugging
- _.unescape to unescape strings escaped by _.escape
- _.where for filtering collections by contained properties
- _.countBy, _.groupBy, _.sortedIndex, and _.uniq accept a
thisArg
argument - _.contains, _.size, _.toArray, and more… accept strings
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 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.
lodash backbone
- CSP builds, supporting default Content Security Policy restrictions, may be created using the
csp
modifier argument.
lodash csp
- Legacy builds, tailored for older browsers without ES5 support, may be created using the
legacy
modifier argument.
lodash legacy
- Mobile builds, with IE < 9 bug fixes and method compilation removed, may be created using the
mobile
modifier argument.
lodash mobile
- Strict builds, with
_.bindAll
,_.defaults
, and_.extend
in strict mode, may be created using thestrict
modifier argument.
lodash strict
- Underscore builds, with iteration fixes removed and only Underscore’s API, may be created using the
underscore
modifier argument.
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 are “arrays”, “chaining”, “collections”, “functions”, “objects”, and “utilities”.
lodash category=collections,functions
lodash category="collections, functions"
- Use the
exclude
argument to pass comma separated names of methods to exclude from the build.
lodash exclude=union,uniq,zip
lodash exclude="union, uniq, zip"
- Use the
exports
argument to pass comma separated names of ways to export theLoDash
function.
Valid exports are “amd”, “commonjs”, “global”, “node”, and “none”.
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.
lodash iife="!function(window,undefined){%output%}(this)"
- Use the
include
argument to pass comma separated names of methods to include in the build.
lodash include=each,filter,map
lodash include="each, filter, map"
All arguments, except exclude
with include
and legacy
with csp
/mobile
, may be combined.
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
.
In browsers:
<script src="lodash.js"></script>
Using npm:
npm install lodash
npm install -g lodash
In Node.js and RingoJS v0.8.0+:
var _ = require('lodash');
In 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
length
property [#148, #154, #252, #448, #659, test] - Ensure “Arrays”, “Collections”, and “Objects” methods don’t error when passed falsey arguments [#650, test]
- Ensure “Collections” methods allow string
collection
arguments [#247, #276, #561, test] - Fix cross-browser object iteration bugs [#60, #376, test]
- Methods should work on pages with incorrectly shimmed native methods [#7, #742, test]
- Register as an AMD module, but still export to global [#431, test]
_.clone
should allowdeep
cloning [#595, test]_.contains
should work with strings [#667, test]_.extend
should recursively extend objects [#379, #718, test]_.forEach
should be chainable [#142, test]_.forEach
should allow exiting iteration early [#211, test]_.isEmpty
should support jQuery/MooTools DOM query collections [#690, test]_.isObject
should avoid V8 bug #2291 [#605, test]_.keys
should work witharguments
objects cross-browser [#396, test]_.range
should coerce arguments to numbers [#634, #683, test]_.throttle
should work when called in a loop [#502, test]
_.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
_.where
_.without
_.wrap
_.zip
- plus all
_(…)
method wrappers
- Renamed
_.zipObject
to_.object
- Replaced
_.drop
with_.omit
- Made
_.drop
alias_.rest
- Added _.invert, _.pairs, and _.random
- Added
_.result
to thebackbone
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 forundefined
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
supportunderscore.js
- Reduced the size of
mobile
andunderscore
builds - Simplified
_.isEqual
and_.size
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.