Cross browser xmlhttprequest get

gistfile1.coffee

# Cross browser xmlhttprequest function (based on http://www.quirksmode.org/js/xmlhttp.html)
xhrGet = do ->

  XMLHttpFactories = [
  	-> new XMLHttpRequest()
  	-> new ActiveXObject("Msxml2.XMLHTTP")
  	-> new ActiveXObject("Msxml3.XMLHTTP")
  	-> new ActiveXObject("Microsoft.XMLHTTP")]

  createXHR = ->
    xhr = null
    for factory in XMLHttpFactories
      if (try xhr = factory())
        createXHR = -> factory() # memoize the factory that worked
        break
    xhr

  (url) ->
    xhr = createXHR()
    deferred = new Deferred()
    return unless xhr
    xhr.open("GET", url, true)
    xhr.onreadystatechange = ->
      return unless xhr.readyState == 4
      success = 200 <= xhr.status < 300 || xhr.status == 304
      deferred[if success then 'resolve' else 'reject'](xhr.responseText)
    xhr.send()
    deferred