How do I fully clear Firefox's cache of CSS and JavaScript files?

I work on a website at my work. The issue is that if I visit the site, which uses the cached versions of the CSS and JavaScript files, and then upload an updated copy of a CSS/JavaScript file, Firefox will still use the cached version.

I can go to 'Tools->Clear Recent History' and clear the Cache of "Everything" and it still uses the cached version of the files. It will eventually updated and use the new files, but it can takes hours for this change to occur.

So, how do I completely clear Firefox's cache of these files?

I have had good use of this Addon: Clear Cache Button

Another option is when refreshing the page, click Ctrl+F5 or Ctrl+Shift+R instead of just F5. This will refresh and overwrite any cache that Firefox has of that page. This is supported by this Mozilla web page.