text: 'use strict';
  
  function createXhr(method) {
      //if IE and the method is not RFC2616 compliant, or if XMLHttpRequest
      //is not available, try getting an ActiveXObject. Otherwise, use XMLHttpRequest
      //if it is available
      if (msie <= 8 && (!method.match(/^(get|post|head|put|delete|options)$/i) ||
        !window.XMLHttpRequest)) {
        return new window.ActiveXObject("Microsoft.XMLHTTP");
      } else if (window.XMLHttpRequest) {
        return new window.XMLHttpRequest();
      }
  
      throw minErr('$httpBackend')('noxhr', "This browser does not support XMLHttpRequest.");
  }
  
  /**
   * @ngdoc service
   * @name $httpBackend
   * @requires $window
   * @requires $document
   *
   * @description
   * HTTP backend used by the {@link ng.$http service} that delegates to
   * XMLHttpRequest object or JSONP and deals with browser incompatibilities.
   *
   * You should never need to use this service directly, instead use the higher-level abstractions:
   * {@link ng.$http $http} or {@link ngResource.$resource $resource}.
   *
   * During testing this implementation is swapped with {@link ngMock.$httpBackend mock
   * $httpBackend} which can be trained with responses.
   */
  function $HttpBackendProvider() {
    this.$get = ['$browser', '$window', '$document', function($browser, $window, $document) {
      return createHttpBackend($browser, createXhr, $browser.defer, $window.angular.callbacks, $document[0]);
    }];
  }
  
  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;
        };
  
        var jsonpDone = jsonpReq(url.replace('JSON_CALLBACK', 'angular.callbacks.' + callbackId),
            function() {
          if (callbacks[callbackId].data) {
            completeRequest(callback, 200, callbacks[callbackId].data);
          } else {
            completeRequest(callback, status || -2);
          }
          callbacks[callbackId] = angular.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;
  
            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;
            }
  
            completeRequest(callback,
                status || xhr.status,
                response,
                responseHeaders,
                xhr.statusText || '');
          }
        };
  
        if (withCredentials) {
          xhr.withCredentials = true;
        }
  
        if (responseType) {
          try {
            xhr.responseType = responseType;
          } catch (e) {
            // WebKit added support for the json responseType value on 09/03/2013
            // https://bugs.webkit.org/show_bug.cgi?id=73648. Versions of Safari prior to 7 are
            // known to throw when setting the value "json" as the response type. Other older
            // browsers implementing the responseType
            //
            // The json response type can be ignored if not supported, because JSON payloads are
            // parsed on the client-side regardless.
            if (responseType !== 'json') {
              throw e;
            }
          }
        }
  
        xhr.send(post || null);
      }
  
      if (timeout > 0) {
        var timeoutId = $browserDefer(timeoutRequest, timeout);
      } else if (timeout && timeout.then) {
        timeout.then(timeoutRequest);
      }
  
  
      function timeoutRequest() {
        status = ABORTED;
        jsonpDone && jsonpDone();
        xhr && xhr.abort();
      }
  
      function completeRequest(callback, status, response, headersString, statusText) {
        // cancel timeout and subsequent timeout promise resolution
        timeoutId && $browserDefer.cancel(timeoutId);
        jsonpDone = xhr = null;
  
        // 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;
        }
  
        // normalize IE bug (http://bugs.jquery.com/ticket/1450)
        status = status === 1223 ? 204 : status;
        statusText = statusText || '';
  
        callback(status, response, headersString, statusText);
        $browser.$$completeOutstandingRequest(noop);
      }
    };
  
    function jsonpReq(url, done) {
      // we can't use jQuery/jqLite here because jQuery does crazy shit with script elements, e.g.:
      // - fetches local scripts via XHR and evals them
      // - adds and immediately removes script elements from the document
      var script = rawDocument.createElement('script'),
          doneWrapper = function() {
            script.onreadystatechange = script.onload = script.onerror = null;
            rawDocument.body.removeChild(script);
            if (done) done();
          };
  
      script.type = 'text/javascript';
      script.src = url;
  
      if (msie && msie <= 8) {
        script.onreadystatechange = function() {
          if (/loaded|complete/.test(script.readyState)) {
            doneWrapper();
          }
        };
      } else {
        script.onload = script.onerror = function() {
          doneWrapper();
        };
      }
  
      rawDocument.body.appendChild(script);
      return doneWrapper;
    }
  }
  