Remove duplicate values from an array. Fastest ES5 implementation.
Last updated 4 years ago by jonschlinkert .
MIT · Repository · Bugs · Original npm · Tarball · package.json
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Remove duplicate values from an array. Fastest ES5 implementation.


Install with npm:

$ npm install --save array-unique


var unique = require('array-unique');

var arr = ['a', 'b', 'c', 'c'];
console.log(unique(arr)) //=> ['a', 'b', 'c']
console.log(arr)         //=> ['a', 'b', 'c']

/* The above modifies the input array. To prevent that at a slight performance cost: */
var unique = require("array-unique").immutable;

var arr = ['a', 'b', 'c', 'c'];
console.log(unique(arr)) //=> ['a', 'b', 'c']
console.log(arr)         //=> ['a', 'b', 'c', 'c']


Related projects

  • arr-diff: Returns an array with only the unique values from the first array, by excluding all… more | homepage
  • arr-flatten: Recursively flatten an array or arrays. This is the fastest implementation of array flatten. | homepage
  • arr-map: Faster, node.js focused alternative to JavaScript's native array map. | homepage
  • arr-pluck: Retrieves the value of a specified property from all elements in the collection. | homepage
  • arr-reduce: Fast array reduce that also loops over sparse elements. | homepage
  • arr-union: Combines a list of arrays, returning a single array with unique values, using strict equality… more | homepage


Pull requests and stars are always welcome. For bugs and feature requests, please create an issue.

Building docs

(This document was generated by verb-generate-readme (a verb generator), please don't edit the readme directly. Any changes to the readme must be made in

To generate the readme and API documentation with verb:

$ npm install -g verb verb-generate-readme && verb

Running tests

Install dev dependencies:

$ npm install -d && npm test


Jon Schlinkert


Copyright © 2016, Jon Schlinkert. Released under the MIT license.

This file was generated by verb-generate-readme, v0.1.28, on July 31, 2016.

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