Function createHttpBackend

test/angular/1.7/angular.js:13466–13643

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

}

function createHttpBackend($browser, createXhr, $browserDefer, callbacks, rawDocument) {
  // TODO(vojta): fix the signature
  return function(method, url, post, callback, headers, timeout, withCredentials, responseType, eventHandlers, uploadEventHandlers) {
    url = url || $browser.url();

    if (lowercase(method) === 'jsonp') {
      var callbackPath = callbacks.createCallback(url);
      var jsonpDone = jsonpReq(url, callbackPath, function(status, text) {
        // jsonpReq only ever sets status to 200 (OK), 404 (ERROR) or -1 (WAITING)
        var response = (status === 200) && callbacks.getResponse(callbackPath);
        completeRequest(callback, status, response, '', text, 'complete');
        callbacks.removeCallback(callbackPath);
      });
    } else {

      var xhr = createXhr(method, url);
      var abortedByTimeout = false;

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

      xhr.onload = function requestLoaded() {
        var statusText = xhr.statusText || '';

        // responseText is the old-school way of retrieving response (supported by IE9)
        // response/responseType properties were introduced in XHR Level2 spec (supported by IE10)
        var response = ('response' in xhr) ? xhr.response : xhr.responseText;

        // normalize IE9 bug (http://bugs.jquery.com/ticket/1450)
        var status = xhr.status === 1223 ? 204 : xhr.status;

        // fix status code when it is 0 (0 status is undocumented).
        // Occurs when accessing file resources or on Android 4.1 stock browser
        // while retrieving files from application cache.
        if (status === 0) {
          status = response ? 200 : urlResolve(url).protocol === 'file' ? 404 : 0;
        }

        completeRequest(callback,
            status,
            response,
            xhr.getAllResponseHeaders(),
            statusText,
            'complete');
      };

      var requestError = function() {
        // The response is always empty
        // See https://xhr.spec.whatwg.org/#request-error-steps and https://fetch.spec.whatwg.org/#concept-network-error
        completeRequest(callback, -1, null, null, '', 'error');
      };

      var requestAborted = function() {
        completeRequest(callback, -1, null, null, '', abortedByTimeout ? 'timeout' : 'abort');