The catch that never fired

Sun, 13 Nov 2011 00:00:00 +0000

The page loads the same in every browser. The bug shows up in one of them, and never where I’m looking.

An iframe on the page needs to know where its parent lives – the URL in the top window. Different origin, so the same-origin policy is in play and the browser is allowed to refuse. I expect it to refuse. I wrote the code expecting it:

try {
 var url = window.top.location.href;
 useIt(url);
} catch (e) {
 fallBack();
}

In Firefox this does exactly what I planned. Reaching across origins for location.href throws – Permission denied to get property Location.href – the catch fires, fallBack() runs, the page copes. IE throws too. The spec, as I read it, says it should.

Javascript on vnykmshr

The catch that never fired