Enable JavaScript in URL bar in Firefox

Solution 1:

browser.urlbar.filter.javascript: false doesn't seem to work.

Indeed it doesn't. You can work around it using Bookmarks (at least until Mozilla block that as well):

• Set up a Bookmark with the location: javascript:%s

• Set the keyword for that bookmark as: javascript

Now you can run JavaScript from the address bar in the format: javascript alert('Hello World') which is very similar to the old javascript:alert('Hello World') method - it's just that the colon needs to be replaced by a space.

Source Executing JavaScript in Firefox address bar - AutoHotkey Community