如果未触发JavaScript EventListener，如何运行代码？

Question

I have a page (we'll call it the parent page) that contains an iframe with another page's content in it (we'll call it the child page).

The 2 pages are hosted on different domains.

If the child page does not load, I want to change the location of the child page to a default page.

I am using window.postMessage to communicate between the 2 pages. I've successfully sent a message to the child page from the parent page and the child page has successfully sent a message back.

I am using eventListeners on both pages to listen for the message. My intent is that if the parent does not receive a message back within a certain timeframe, it should change the location and load the default page.

Is there a way to run a function if the parent page's eventListener is NOT triggered in a certain amount of time?

Or is there another way to accomplish the goal that I'm not thinking of?

Answer 1

You could do something like the following:

var onNoEvent = setTimeout(function(){
  //... do your thing
}, 3000);

window.addEventListener('message', function(){
  clearTimeout(onNoEvent); //cancel the timeout event

}, false);