Earlier quoted context omitted.
You can assign a keyboard shorcut to that easily (I bound it to Cmd+Shift+J and find it super-handy): https://support.apple.com/en-gb/guide/mac-help/mchlp2271/mac If someone knows how to achieve the same on Linux for Chrome and Firefox, I'd love to hear it (browser plugins are a bit of a security and stability shitshow, so non-plugin solution would be preferred, all else being equal).
Mozilla removed the normal settings toggle a while back, so your options are to manually set javascript.enabled in about:config or use an extension. I agree in general that extensions aren't great, but I trust uBlock. I think Chrome actually is fine although I don't know of a keybinding for it: Don't they still have a toggle right in the site menu (click the icon to the left of the URL to toggle all kinds of these th…
It's about the best UI I could come up with for this particular knob and the other things adjacent to it.