How to force the browser to reload cached CSS/JS files?

Question

I have noticed that some browsers (in particular, Firefox and Opera) are very zealous in using cached copies of .css and .js files, even be

Answer 1

Dont use foo.css?version=1! Browsers aren't supposed to cache URLs with GET variables. According to http://www.thinkvitamin.com/features/webapps/serving-javascript-fast, though IE and Firefox ignore this, Opera and Safari don't! Instead, use foo.v1234.css, and use rewrite rules to strip out the version number.