'load' event not firing when iframe is loaded in Chrome

Unfortunately it is not possible to use an iframe's onload event in Chrome if the content is an attachment. This answer may provide you with an idea of how you can work around it.

I hate this, but I couldn't find any other way than checking whether it is still loading or not except by checking at intervals.

var timer = setInterval(function () {
    iframe = document.getElementById('iframedownload');
    var iframeDoc = iframe.contentDocument || iframe.contentWindow.document;
    // Check if loading is complete
    if (iframeDoc.readyState == 'complete' || iframeDoc.readyState == 'interactive') {
        loadingOff();
        clearInterval(timer);
        return;
    }
}, 4000);