How can I make it so that the images associated with my chat, or at least SOME of them, don't cache and are always loaded from the server?

Every time a user picture is changed or I update a button, etc, the users come in and see the old one.

Try this meta tag:



The directive CACHE-CONTROL:NO-CACHE indicates cached information should not be used and instead requests should be forwarded to the origin server. This directive has the same semantics as the PRAGMA:NO-CACHE.
Clients SHOULD include both PRAGMA:NO-CACHE and CACHE-CONTROL:NO-CACHE when a no-cache request is sent to a server not known to be HTTP/1.1 compliant.
Also see EXPIRES.
Note: It may be better to specify cache commands in HTTP than in META statements, where they can influence more than the browser, but proxies and other intermediaries that may cache information.

or this one:



This directive indicates cached information should not be used and instead requests should be forwarded to the origin server. This directive has the same semantics as the CACHE-CONTROL:NO-CACHE directive and is provided for backwards compatibility with HTTP/1.0.
Clients SHOULD include both PRAGMA:NO-CACHE and CACHE-CONTROL:NO-CACHE when a no-cache request is sent to a server not known to be HTTP/1.1 compliant.
HTTP/1.1 clients SHOULD NOT send the PRAGMA request-header. HTTP/1.1 caches SHOULD treat "PRAGMA:NO-CACHE" as if the client had sent "CACHE-CONTROL:NO-CACHE".

This may sound stupid but how do I...

It may be better to specify cache commands in HTTP than in META statements, where they can influence more than the browser, but proxies and other intermediaries that may cache information.

do this?

This could help => w3.org/Protocols/rfc2616/rfc2616-sec13.html

It’s even easier if you use Cache-Control: max-age;



This will make the script cacheable for 10 minutes after the request, so that if the user hits the ‘back’ button, they won’t be resubmitting the request.