Question

Here is the situation:

• A page (iframe.html) has an iframe loading another page (iframe-content.html).
• An JavaScript error might happen when iframe-content.html is loaded in the iframe.
• I’d like that exception to be visible to the browser (e.g. shown in Firefox error console, or Firebug).

Here is what I see:

1. When iframe.html is initially loaded, and loads iframe-content.html with src='iframe-content.html', the JavaScript exception shows in Firebug.
2. However, if the page is loaded in JavaScript (document.getElementById('iframe').src = 'iframe-content.html'), the exception doesn’t show.

You can reproduce this by going to:

1. http://avernet.googlepages.com/iframe.html with Firefox.
2. You’ll see the exception as iframe-content.html is loaded.
3. Click on the button: the content of the iframe is loaded again, but this time the exception doesn’t show in Firebug.

Is there a way at #3 to have the exception show, instead of it being silently ignored? (You can’t use a try/catch around the JS code that sets the src, as this code returns immediately before the page is loaded in the iframe.)

Answer 1

It seems that your iframe page is not really loaded on the second time. Or it’s loaded from the cache and the error is ignored. This is interesting, but I think I found an way around it.

function setContent() {     try {         console.log('Loading iframe content');         document.getElementById('iframe').src = 'iframe-content.html?foo=bar';     } catch (e) {         console.log('Caught', e);     }     console.log('Done loading'); } 

With that the error should appear.

What I did, was to trick the browser to think that I’m loading a brand new page as the parameters after the url have changed.

'iframe-content.html?foo=bar'; 

You could replace my ‘bar’ string with a changing timestamp. Sure, it would avoid the cache, but it would also force it to generate the error like you wished.