Function pollDomTrigger

packages/core/src/defer/dom_triggers.ts:145–206

()

  const zone = injector.get(NgZone);
  let poll: AfterRenderRef;
  function pollDomTrigger() {
    // If the initial view was destroyed, we don't need to do anything.
    if (isDestroyed(initialLView)) {
      poll.destroy();
      return;
    }

    const lDetails = getLDeferBlockDetails(initialLView, tNode);
    const renderedState = lDetails[DEFER_BLOCK_STATE];

    // If the block was loaded before the trigger was resolved, we don't need to do anything.
    if (
      renderedState !== DeferBlockInternalState.Initial &&
      renderedState !== DeferBlockState.Placeholder
    ) {
      poll.destroy();
      return;
    }

    const triggerLView = getTriggerLView(initialLView, tNode, walkUpTimes);

    // Keep polling until we resolve the trigger's LView.
    if (!triggerLView) {
      // Keep polling.
      return;
    }

    poll.destroy();

    // It's possible that the trigger's view was destroyed before we resolved the trigger element.
    if (isDestroyed(triggerLView)) {
      return;
    }

    const element = getTriggerElement(triggerLView, triggerIndex);
    const cleanup = registerFn(
      element,
      () => {
        // `pollDomTrigger` runs outside the zone (because of `afterNextRender`) and registers its
        // listeners outside the zone, so we jump back into the zone prior to running the callback.
        zone.run(() => {
          if (initialLView !== triggerLView) {
            removeLViewOnDestroy(triggerLView, cleanup);
          }
          callback();
        });
      },
      injector,
      options,
    );

    // The trigger and deferred block might be in different LViews.
    // For the main LView the cleanup would happen as a part of
    // `storeTriggerCleanupFn` logic. For trigger LView we register
    // a cleanup function there to remove event handlers in case an
    // LView gets destroyed before a trigger is invoked.
    if (initialLView !== triggerLView) {
      storeLViewOnDestroy(triggerLView, cleanup);