You can effectively disable JavaScript with WebExtensions by injecting a script that overwrites all the properties of the document and window with undefined. In

You can effectively disable JavaScript with WebExtensions by injecting a script that overwrites all the properties of the document and window with undefined. Instantly crashes pretty much any script. If you want to do it sometime after page load, you could replace all those properties with a Proxy object instead, and have that object start throwing errors for any access after X time has passed.