I think there should be a 'Disable/Enable JavaScript' option and a list of exceptions in the Settings/Security page. If we enable JavaScript, Firefox should disable JavaScript for websites in the exceptions list. Or something like that. There are some websites where I want to disable some features like JavaScript, but I want them enabled on most websites. So I don't want to enable/disable JavaScript for all websites.
Or it could be the settings menu for each website in the top left (where the security icon appears). After changing the settings on a website, Firefox can save what was changed on the website and remember it when we open that website again.