How do I add a loading indicator to my page while my iframe loads?

Is there any reason you can't listen to the onload event of the iframe itself? It should fire after the child content has loaded.

Something like this:

showLoader();
$('#mydiv').html('<iframe src="sourcelink.html" frameborder="0" width="760" height="2400" scrolling="no"></iframe>');
$('#mydiv iframe').load(function() { hideLoader(); }