Function createHttpBackend

test/angular/1.2/angular.js:8570–8745

($browser, createXhr, $browserDefer, callbacks, rawDocument)

}

function createHttpBackend($browser, createXhr, $browserDefer, callbacks, rawDocument) {
  var ABORTED = -1;

  // TODO(vojta): fix the signature
  return function(method, url, post, callback, headers, timeout, withCredentials, responseType) {
    var status;
    $browser.$$incOutstandingRequestCount();
    url = url || $browser.url();

    if (lowercase(method) == 'jsonp') {
      var callbackId = '_' + (callbacks.counter++).toString(36);
      callbacks[callbackId] = function(data) {
        callbacks[callbackId].data = data;
        callbacks[callbackId].called = true;
      };

      var jsonpDone = jsonpReq(url.replace('JSON_CALLBACK', 'angular.callbacks.' + callbackId),
          callbackId, function(status, text) {
        completeRequest(callback, status, callbacks[callbackId].data, "", text);
        callbacks[callbackId] = noop;
      });
    } else {

      var xhr = createXhr(method);

      xhr.open(method, url, true);
      forEach(headers, function(value, key) {
        if (isDefined(value)) {
            xhr.setRequestHeader(key, value);
        }
      });

      // In IE6 and 7, this might be called synchronously when xhr.send below is called and the
      // response is in the cache. the promise api will ensure that to the app code the api is
      // always async
      xhr.onreadystatechange = function() {
        // onreadystatechange might get called multiple times with readyState === 4 on mobile webkit caused by
        // xhrs that are resolved while the app is in the background (see #5426).
        // since calling completeRequest sets the `xhr` variable to null, we just check if it's not null before
        // continuing
        //
        // we can't set xhr.onreadystatechange to undefined or delete it because that breaks IE8 (method=PATCH) and
        // Safari respectively.
        if (xhr && xhr.readyState == 4) {
          var responseHeaders = null,
              response = null,
              statusText = '';

          if(status !== ABORTED) {
            responseHeaders = xhr.getAllResponseHeaders();

            // responseText is the old-school way of retrieving response (supported by IE8 & 9)
            // response/responseType properties were introduced in XHR Level2 spec (supported by IE10)
            response = ('response' in xhr) ? xhr.response : xhr.responseText;
          }

          // Accessing statusText on an aborted xhr object will
          // throw an 'c00c023f error' in IE9 and lower, don't touch it.