External Javascript Timeout

Question

I have a number of tracking scripts and web services installed on my website and I noticed when one of the services goes down, it still tries to call the external javascript file hosted on a different server. In Firefox, Chrome and other new browsers, there doesn't seem to be any issues when one of the services go down. However, in IE7 and IE8, my pages don't load all the way and time out before everything is displayed. Is there any way to add a time out on these javascript calls to prevent them from breaking my pages when they go down?

Answer 1

Try adding defer="defer"

The defer attribute gives a hint to the browser that the script does not create any content so the browser can optionally defer interpreting the script. This can improve performance by delaying execution of scripts until after the body content is parsed and rendered.

Edit
This will prevent those scripts from running until the page loads:

function loadjs(filename) {
    var fileref=document.createElement('script');
    fileref.setAttribute("type","text/javascript");
    fileref.setAttribute("src", filename);
}

window.onLoad = function() {
   loadJs("http://path.to.js");
   loadJs("http://path.to2.js");
   ...
}

Answer 2

You can load them dynamically after page load with JS. If the JS files are on a different server, the browser will still show a "browser busy" indicator when you do that, but the original page will load.

If you can fetch the JS from your own site, you can load it with XMLHttpRequest after page load (or with your favorite JS library's helpers, e.g. jQuery's $.ajax(...)) and then eval it. This way the fetching itself won't show the browser-busy indicator.

To fetch the JS from your own site, you can download it from your tracking provider (which won't be officially supported but usually works) - just remember to refetch new versions every once in a while - or you can create a "forwarding" service on your own site that fetches it from the tracking provider and caches it locally for a while. This way your JS won't be in danger of staleness.

Steve Souders has more information about deferred loading of scripts and browser-busy indicators.