Totally agree with @Ambikayache been using DevTools this way for accessibility audits and fallback testing for about 4 years. Just to build on that, there’s an even quicker way I use via the Command Menu:
- With DevTools open, press Ctrl+Shift+P (or Cmd+Shift+P on Mac).
- Start typing: Disable JavaScript.
- Select the option and hit enter.
- Refresh the page.
This is super fast if you’re jumping between tabs or testing how features fail gracefully. Especially useful when checking if something like a javascript time function fallback (like a countdown or delay) degrades correctly when JS is off. 
