What is lodash?
Lodash is a JavaScript library that provides utility functions for common programming tasks using a functional programming paradigm. It includes functions for manipulating and traversing arrays, objects, and strings, as well as utilities for functions, language, math, number, object, sequence, and utility methods.
What are lodash's main functionalities?
Array Manipulation
Lodash provides a rich set of array manipulation functions such as map, filter, find, and sort. The code sample demonstrates sorting an array in ascending order using a custom comparator.
[3, 2, 1].sort(_.compareWith(function(a, b) { return a - b; }))
Object Manipulation
Lodash allows for easy manipulation and traversal of objects. The code sample shows how to assign properties from source objects to a destination object.
_.assign({ 'a': 1 }, { 'b': 2 }, { 'c': 3 })
String Manipulation
Lodash includes functions to manipulate strings, such as converting to different cases, trimming, padding, etc. The code sample demonstrates converting a string to kebab-case.
_.kebabCase('Foo Bar')
Function Utilities
Lodash provides function utilities like debounce and throttle to control function invocation. The code sample shows a debounced function that will only be invoked after 250 milliseconds have passed without it being called again.
_.debounce(function() { console.log('Debounced'); }, 250)
Language Utilities
Lodash includes utilities for deep cloning, merging, and comparing objects. The code sample demonstrates deep cloning an object to ensure nested objects are cloned as well.
_.cloneDeep({ 'a': 1, 'b': { 'c': 2 } })
Other packages similar to lodash
underscore
Underscore is a utility library with similar functionality to Lodash, offering a range of functions for manipulating arrays, objects, and functions. It is generally considered to be the predecessor to Lodash, which provides a superset of Underscore's features with additional performance optimizations.
ramda
Ramda is a functional programming library that emphasizes a more functional and composable approach compared to Lodash. It provides similar utilities but focuses on immutability and side-effect free functions, which can lead to a different programming style.
immutable
Immutable.js offers a different take on data manipulation by providing persistent immutable data structures. Unlike Lodash, which works with standard JavaScript objects and arrays, Immutable.js uses its own data structures, which can lead to better performance and easier reasoning about state changes in certain applications.
Lo-Dash v0.8.1
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.
Download
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 5-22, Firefox 1-15, IE 6-10, Opera 9.25-12, Safari 3-6, Node.js 0.4.8-0.8.11, 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.
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 the strict
modifier argument.
lodash strict
- Underscore builds, tailored for projects already using Underscore, 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 (case-insensitive) are “arrays”, “chaining”, “collections”, “functions”, “objects”, and “utilities”.
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”.
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.
lodash iife="!function(window,undefined){%output%}(this)"
- Use the
include
argument to pass comma separated method/category names to include in the build.
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.
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.
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
lodash template="./*.jst"
- Use the
settings
argument to pass the template settings used when precompiling templates
lodash settings="{interpolate:/\\{\\{([\\s\\S]+?)\\}\\}/g}"
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:
<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);
});
Resolved Underscore.js issues
- Add AMD loader support [#431, test]
- Allow iteration of objects with a
length
property [#799, test] - Ensure “Arrays”, “Collections”, and “Objects” methods don’t error when passed falsey arguments [#650, #803, 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]
_.clone
should allow deep
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 with arguments
objects cross-browser [#396, test]_.range
should coerce arguments to numbers [#634, #683, test]_.throttle
should work when called in a loop [#502, test]
Optimized methods (50+)
_.bind
_.bindAll
_.compact
_.contains
, _.include
_.defaults
_.difference
_.each
_.every
, _.all
_.extend
_.filter
, _.select
_.find
, _.detect
_.flatten
_.forEach
, _.each
_.functions
, _.methods
_.groupBy
_.indexOf
_.intersection
_.invert
_.invoke
_.isArguments
_.isDate
_.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
_.toArray
_.union
_.uniq
, _.unique
_.values
_.where
_.without
_.wrap
_.zip
- plus all
_(…)
method wrappers
Release Notes
v0.8.1
- Made
underscore
build include deep clone when clone
is requested via include
or plus
- Reverted removal of first argument falsey checks from methods
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