OnError Behaving Differently Between Browsers

I'm trying to get the onError event to work but so far it only works in Internet Explorer 9. I have tried several codes but basically it comes down to this: onerror="this.src='images/no_image.png';">

Edit: Sidestepping the issue with proper handling of asap.imgurl would look like this:

<img class="a_toc_image" src="' + (asap.imgurl != "" ? asap.imgurl:"/images/no_image.png") + '">