Window.frames[0].document.onkeydown not working in Firefox?

Question

Mozilla Firefox

Hello people!
I'm dying here trying to figure out what the problem is. I have a code

ste.frame.document.onkeydown=function(e) {<br/>
 alert('a');<br/>
};

Here ste.frame is [object Window]. That is, it is almost identical to this:

window.frames[0].document.onkeydown=function(e){<br/>
 alert('a');<br/>
}

The code works in IE and Chrome but doesn't want to work in Firefox. When I tested in jsfiddle.net, the event is processed, but not directly. Here is the code for the test:

&lt;iframe&gt;&lt;/iframe&gt;<br/>
&lt;script type=&quot;text/javascript&quot;&gt;<br/>
 window.frames[0].document.onkeydown=function(e){<br/>
 alert('a');<br/>
 }<br/>
&lt;/script&gt;

Google did not give anything - has anyone met with this or maybe knows what needs to be done to make FF work out this event?

Answer 1

I have it working like this:

document.addEventListener('DOMContentLoaded', function(){

  window.frames[0].document.onkeydown=function(e){

    alert('a');

  };
  
});

Answer 2

Thanks - both options work, but not in the code of the desired plugin. Solved the problem in a different way :).