There often comes a time when you are working on a large project and find a need to refactor javascript resources. Unfortunately, if those assets are accessed by 3rd parties or other code you cannot easily update, you might find yourself stuck.
If you have access to the Tier1 (HTTP server such as ApacheHTTPd) you can often do this within the httpd.conf, or an .htaccess file update. If not, you can always do a simple function within the old javascript file itself, such as the one below.
Put this in the old javascript file location, it is in a closure to prevent the variables from “leaking” into the global namespace.
/* MOVED */
(function(){
"use strict";
var u='/js/newfile.js';
var t=document.createElement('script');t.type='text/javascript';t.src=u;
var s=document.getElementsByTagName('script')[0];s.parentNode.insertBefore(t,s);
})();