[rmrfrmrf]

    <script src="//ajax.googleapis.com/ajax/libs/jquery/2.0.3/jquery.min.js"></script>
    <script>window.jQuery || document.write('<script src="path/to/your/jquery"><\/script>')</script>

Source: http://stackoverflow.com/questions/1014203/best-way-to-use-g...

[youngtaff]

I'd question whether this is a worthwhile fallback as depending on what the error is then the browser may still wait 30 (ish) seconds for the original request to time out.

[rmrfrmrf]

I look forward to seeing what you come up with.