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60

Ordered hash in JavaScript

rated 0 times [ 62] [ 2] / answers: 1 / hits: 32409 / 14 Years ago, sun, may 9, 2010, 12:00:00

JavaScript objects have no order stored for properties (according to the spec). Firefox seems to preserve the order of definition of properties when using a for...in loop. Is this behaviour something that I can rely on? If not is there a piece of JavaScript code somewhere that implements an ordered hash type?

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laytonlamontm

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3 Years ago

answered 14 Years ago brynn · Accepted Answer

This question come up as the top search result. After not finding a ordered hash, i just wrote this small coffescript. Hopefully this will help folks landing on this page:

## OrderedHash

# f = new OrderedHash

# f.push('a', 1)

# f.keys()

# 

class OrderedHash

 constructor: ->

   @m_keys = []

   @m_vals = {}



  push: (k,v) ->

    if not @m_vals[k]

      @m_keys.push k

    @m_vals[k] = v



  length: () -> return @m_keys.length



  keys: () -> return @m_keys



  val: (k) -> return @m_vals[k]

  vals: () -> return @m_vals