An extension to native Array which supports direct element lookup by position index or primary key.
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An extension to native Array which supports direct element lookup by position index or primary key. Objects returned by IndexedArray are Array-like, meaning they have a .length property and are instanceof Array.


var IndexedArray = require('indexed-array')

var data = [
  {_id: 'abc', name: 'Kurosawa'},
  {_id: 'xyz', name: 'Gondry'},
  {_id: 'rst', name: 'Almodovar'}

var arr = IndexedArray(data)
arr['abc'].name; // 'Kurosawa'
arr[0].name;     // 'Kurosawa'
arr['rst'].name; // 'Almodovar'
arr[2].name;     // 'Almodovar'

The IndexedArray constructor takes an optional existing Array and an optional indexer, which can be either the name of the property to index or a function like you would pass to By default, MongoDB style _id is used.

var arrByName = IndexedArray(data, 'name')
arrByName['Kurosawa']._id; // => 'abc'

var arrByName2 = IndexedArray(data, function (x) { return })
arrByName2['almodovar']._id; // => 'rst'

You can also create an IndexedArray from an object being used as a hashmap:

var obj = {
  'QWE': {val: 'qwe'},
  'ASD': {val: 'asd'},
  'ZXC': {val: 'zxc'}

var arr = IndexedArray.fromObject(obj)

Now you can use Array-like methods, such as push and pop while still being able to access objects in O(1) time without iteration.

When you're done mutating the IndexedArray, you can get the the hashmap directly:


IndexedArray supports normal Array.prototype methods:

  • pop
  • push
  • shift
  • unshift
  • splice
  • slice

Since IndexedArrays extend plain old Arrays, collection methods work great:

  • forEach
  • map
  • reduce
  • filter
  • some
  • every
  • sort

And third party libraries should play nice, too, for example Lo-Dash or underscore.

See tests for more examples.

AMD Compatibility

IndexedArray supports AMD modules and can be used either in node or in the browser. IndexedArray has no dependencies on node but may require ES5 shims in really old browsers.


$ npm install indexed-array

Running the tests

From project root,

$ npm install
$ npm test


Feel free to open an issue or a pull request.


Copyright (c) 2012 Jason Denizac Licensed under the MIT license.