I know it, however it’s a best practice of accesibility. A example is BBC.co.uk. In https://www.bbc.co.uk/accessibility/ if you deactivates javascript, the widget “change text size and color” is missing.
It would be better still show the widget only if javascript is enabled, but perhaps it’s very difficult to get it.
Screenshot: https://www.imageupload.co.uk/image/ZxXj