Function patchXHR

packages/zone.js/lib/browser/browser.ts:107–289

(window: any)

    }

    function patchXHR(window: any) {
      const XMLHttpRequest = window['XMLHttpRequest'];
      if (!XMLHttpRequest) {
        // XMLHttpRequest is not available in service worker
        return;
      }
      const XMLHttpRequestPrototype: any = XMLHttpRequest.prototype;

      function findPendingTask(target: any) {
        return target[XHR_TASK];
      }

      let oriAddListener = XMLHttpRequestPrototype[ZONE_SYMBOL_ADD_EVENT_LISTENER];
      let oriRemoveListener = XMLHttpRequestPrototype[ZONE_SYMBOL_REMOVE_EVENT_LISTENER];
      if (!oriAddListener) {
        const XMLHttpRequestEventTarget = window['XMLHttpRequestEventTarget'];
        if (XMLHttpRequestEventTarget) {
          const XMLHttpRequestEventTargetPrototype = XMLHttpRequestEventTarget.prototype;
          oriAddListener = XMLHttpRequestEventTargetPrototype[ZONE_SYMBOL_ADD_EVENT_LISTENER];
          oriRemoveListener = XMLHttpRequestEventTargetPrototype[ZONE_SYMBOL_REMOVE_EVENT_LISTENER];
        }
      }

      const READY_STATE_CHANGE = 'readystatechange';
      const SCHEDULED = 'scheduled';

      function scheduleTask(task: Task) {
        const data = <XHROptions>task.data;
        const target = data.target;
        target[XHR_SCHEDULED] = false;
        target[XHR_ERROR_BEFORE_SCHEDULED] = false;
        // remove existing event listener
        const listener = target[XHR_LISTENER];
        if (!oriAddListener) {
          oriAddListener = target[ZONE_SYMBOL_ADD_EVENT_LISTENER];
          oriRemoveListener = target[ZONE_SYMBOL_REMOVE_EVENT_LISTENER];
        }

        if (listener) {
          oriRemoveListener.call(target, READY_STATE_CHANGE, listener);
        }
        const newListener = (target[XHR_LISTENER] = () => {
          if (target.readyState === target.DONE) {
            // sometimes on some browsers XMLHttpRequest will fire onreadystatechange with
            // readyState=4 multiple times, so we need to check task state here
            if (!data.aborted && target[XHR_SCHEDULED] && task.state === SCHEDULED) {
              // check whether the xhr has registered onload listener
              // if that is the case, the task should invoke after all
              // onload listeners finish.
              // Also if the request failed without response (status = 0), the load event handler
              // will not be triggered, in that case, we should also invoke the placeholder callback
              // to close the XMLHttpRequest::send macroTask.
              // https://github.com/angular/angular/issues/38795
              const loadTasks = target[Zone.__symbol__('loadfalse')];
              if (target.status !== 0 && loadTasks && loadTasks.length > 0) {
                const oriInvoke = task.invoke;
                task.invoke = function () {
                  // need to load the tasks again, because in other