Is it the filename or the whole URL used as a key in browser caches?

Question

It\'s common to want browsers to cache resources - JavaScript, CSS, images, etc. until there is a new version available, and then ensure that the browser fetches and caches

Answer 1

The MINIMUM you need to identify an HTTP object is by the full path, including any query-string parameters. Some browsers may not cache objects with a query string but that has nothing to do with the key to the cache.

It is also important to remember that the the path is no longer sufficient. The Vary: header in the HTTP response alerts the browser (or proxy server, etc.) of anything OTHER than the URL which should be used to determine the cache key, such as cookies, encoding values, etc.

To your basic question, yes, changing the URL of the .js file is sufficent. TO the larger question of what determines the cache key, it's the URL plus the Vary: header restrictions.