ASP.NET - Overriding Javascript and Styleheets cached by browser

I'm working on an asp.net website. I need to make sure my javascript and css updates will be immediately available for returning visitors, without them having to clear their cache to get the latest code. How can I force 开发者_StackOverflowthis when needed, and leave it alone on other occasions?

Thanks in advance.

Stackoverflow does this very elegantly IMO. You can see in there source there is a query-string variable passed.

<script type="text/javascript" src="http://sstatic.net/js/stub.js?v=778aaf5a38e2"></script>

This will force new load if that changes.

In order to reliably force a refresh of cached content on the browser you need to change the name / requested URL of the file somehow.

Often this is done by appending a query string to the URL (which is often ignored)

See When Does Browser Automatically Clear JavaScript Cache? for a more complete discussion.

You'll need to apply no-cache header to those resources, alternatively make the url dynamic somehow.

see - http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html