By the way: If the cache should only be emptied to get a web page update earlier or check if updates provided by some developers work, the browser cache must not be emptied at all.

The so-called "incognito mode" that every modern Web browser supports, allows visiting a website in a completely private and from the remaining web browser separated area. This includes a separate history and also a separate cache that is always cleared at the beginning.

In Mozilla Firefox the button for this can be found in the settings menu at the top right. The menu item is called "New private window".

The private window differs visually from the appearance of the standard browser window. In the case of Mozilla Firefox a small mask is displayed in the top right.

Clicking on the three circles at the top right opens the context menu of the browser. There is also the menu item "Settings".

You can then search for "cache" in the search form at the top. The first search result should already be the hit you are looking for.

After clicking on "Manage Data" the "Cached Web Content" can be cleared explicitly. As soon as you click on "Clear" the relevant cache should have been deleted.

I recommend using the developer tools to clear the cache for a specific website. These can also be found via the three dots in the top right of the menu and then under "Web Developer" or "Developer".

"Storage Inspector" can then be selected again in the "Web developer" submenu. After clicking on the mentioned menu item, the browser should split up and the developer tools should appear.

The different storage types and the associated domain now appear on the left-hand side. If you now right-click on an entry, a menu appears with the only entry "Delete all". As soon as this button has been clicked, the corresponding memory is emptied. In doubt, this process must be repeated for each menu item on the left.