I think you need to make the html page none cachable. This is done server side, in php it would be:
header("cache-Control: post-check=0, pre-check=0", false);
header("Expires: Mon, 27 Aug 2007 00:00 GMT");//Some date in the past.
Alternatively you could add a query string, which just has some random data in, to the end of the js file name in your js include
you should probably use a better random number generator for this, usually they incorprate the date and time or something.
Hope this helps.