Array.prototype.reduce shim for non-compliant browsers. Converted from https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/Reduce.

reduce.coffee

# reduce from https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/Reduce
if "function" isnt typeof Array::reduce
  Array::reduce = (callback, opt_initialValue) ->
    "use strict"

    # At the moment all modern browsers, that support strict mode, have
    # native implementation of Array.prototype.reduce. For instance, IE8
    # does not support strict mode, so this check is actually useless.
    throw new TypeError("Array.prototype.reduce called on null or undefined")  if null is this or "undefined" is typeof this
    throw new TypeError(callback + " is not a function")  if "function" isnt typeof callback

    index      = 0
    length     = @length >>> 0
    value      = undefined
    isValueSet = false

    if 1 < arguments_.length
      value      = opt_initialValue
      isValueSet = true

    while length > index
      continue  unless @hasOwnProperty(index)
      if isValueSet
        value = callback(value, this[index], index, this)
      else
        value = this[index]
        isValueSet = true
      ++index

    throw new TypeError("Reduce of empty array with no initial value")  unless isValueSet

    value