Firefox – How to clear the JavaScript file cache in Firefox on every visit in a page

You can force all requests relating to a refresh to actually be requested from the server (bypassing any already cached content, and updating the cache with the new version) by using Ctrl+F5 instead of just F5.

This does not work for requests made by the page within client-side code though. When that is a problem you need to use the POST method (POST requests should never be cached) instead of GET or add an ever-changing value to the query string (such as the current time in ms).

This is a very old question, and Firefox Quantum has happened since it was written. Just to update, there is an add-on that works with Quantum (also available for Chromium-based browsers), called Download All Images by belav (developer's page here), which offers a lot of flexibility in selecting all images or ones meeting various criteria. I've used it a few times. The selection criteria comes in handy on something like an Amazon product page, which has a lot of images you may not want.

Edit: At the time I wrote this answer, this add-on was titled "Download Them All", which could have been confused with the Nils Maier add-on recommended in 2010 by Andrew Richard Gray and Licargon. I just updated the add-on name here to its current title.

Note that the Nils Maier "DownloadThemAll" add-on does now appear to have been rewritten as a WebExtension, and currently looks to be Quantum-compatible. I haven't tested that one.