Function invokeTask

packages/zone.js/lib/common/events.ts:221–252

(task: any, target: any, event: Event)

  const PREPEND_EVENT_LISTENER_SOURCE = '.' + PREPEND_EVENT_LISTENER + ':';

  const invokeTask = function (task: any, target: any, event: Event): Error | undefined {
    // for better performance, check isRemoved which is set
    // by removeEventListener
    if (task.isRemoved) {
      return;
    }
    const delegate = task.callback;
    if (typeof delegate === 'object' && delegate.handleEvent) {
      // create the bind version of handleEvent when invoke
      task.callback = (event: Event) => delegate.handleEvent(event);
      task.originalDelegate = delegate;
    }
    // invoke static task.invoke
    // need to try/catch error here, otherwise, the error in one event listener
    // will break the executions of the other event listeners. Also error will
    // not remove the event listener when `once` options is true.
    let error;
    try {
      task.invoke(task, target, [event]);
    } catch (err: any) {
      error = err;
    }
    const options = task.options;
    if (options && typeof options === 'object' && options.once) {
      // if options.once is true, after invoke once remove listener here
      // only browser need to do this, nodejs eventEmitter will cal removeListener
      // inside EventEmitter.once
      const delegate = task.originalDelegate ? task.originalDelegate : task.callback;
      target[REMOVE_EVENT_LISTENER].call(target, event.type, delegate, options);
    }
    return error;
  };

  function globalCallback(context: unknown, event: Event, isCapture: boolean) {
    // https://github.com/angular/zone.js/issues/911, in IE, sometimes