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A drop-in replacement for Underscore.js that delivers performance improvements, bug fixes, and additional features.

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README.md

Lo-Dash v0.4.2

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.

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Dive in

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.

Screencasts

For more information check out these screencasts over Lo-Dash:

Features

Support

Lo-Dash has been tested in at least Chrome 5-20, Firefox 1.5-13, IE 6-9, Opera 9.25-12, Safari 3.0.4-5.1.7, Node.js 0.4.8-0.8.2, 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.
lodash backbone
  • 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 the strict modifier argument.
lodash strict

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".
lodash category=collections,functions
lodash category="collections, functions"
  1. Use the exclude argument to pass the names of methods to exclude from the build.
lodash exclude=union,uniq,zip
lodash exclude="union, uniq, zip"
  1. Use the include argument to pass the 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 mobile, may be combined.

lodash backbone legacy category=utilities exclude=first,last
lodash backbone mobile strict category=functions include=pick,uniq

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.

Installation and usage

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);
});

Closed Underscore.js issues (20+)

  • Allow iteration of objects with a length property [#148, #154, #252, #448, #659, test]
  • Ensure array-like objects with invalid length properties are treated like regular objects [test, test, test]
  • Ensure "Arrays" methods allow falsey array arguments [test]
  • Ensure "Collections" methods allow string collection arguments [#247, #276, #561, test, test, test, test]
  • Ensure templates compiled with errors are inspectable [#666, test]
  • Fix cross-browser object iteration bugs [#60, #376, test, test, test, test, test, test]
  • Handle arrays with undefined values correctly in IE < 9 [#601]
  • Methods should work on pages with incorrectly shimmed native methods [#7, test]
  • Register as an AMD module, but still export to global [#431, test]
  • _(…) should return passed wrapper instances [test]
  • _.contains should work with strings [#667, test]
  • _.escape should return an empty string when passed null or undefined [#407, test]
  • _.forEach should be chainable [#142, test]
  • _.groupBy should add values to own, not inherited, properties [test]
  • _isNaN(new Number(NaN)) should return true [test]
  • _.reduceRight should pass correct callback arguments when iterating objects [test]
  • _.size should return the length of string values [test]
  • _.size shouldn't error on falsey values [#650, test]
  • _.size should work with arguments objects cross-browser [#653, test]
  • _.sortedIndex should support arrays with high length values [test]
  • _.template should not augment the options object [test]
  • _.throttle should work when called in a loop [#502, test]
  • _.zipObject should accept less than two arguments [test]

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
  • _.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

Release Notes

v0.4.2

  • Added strict build
  • Ensured _.bindAll, _.defaults, and _.extend avoid strict mode errors when attempting to augment read-only properties
  • Optimized the iteration of large arrays in _.difference, _.intersection, and _.without
  • Fixed build bugs related to removing variables

v0.4.1

  • Fixed _.template regression
  • Optimized build process to detect and remove more unused variables

v0.4.0

  • Added bin and scripts entries to package.json
  • Added legacy build option
  • Added cross-browser support for passing strings to "Collections" methods
  • Added _.zipObject
  • Leveraged _.indexOf's fromIndex in _.difference and _.without
  • Optimized compiled templates
  • Optimized inlining the iteratorTemplate for builds
  • Optimized object iteration for "Collections" methods
  • Optimized partially applied _.bind in V8
  • Made compiled templates more debuggable
  • Made _.size work with falsey values and consistent cross-browser with arguments objects
  • Moved _.groupBy and _.sortBy back to the "Collections" category
  • Removed arguments object from _.range

The full changelog is available here.

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

Contributors

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