title: Download Google Sheet data as JSON from browser through custom menu
body: <p>Is there a way to download JSON directly from a Google Sheet, like this:
  <a href="https://i.stack.imgur.com/VIUDZ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/VIUDZ.png" alt="enter image description here" /></a></p>
  <p>I want to create a custom menu with an App Script. There would be a button that would create the JSON object from the sheet data and when it is finished it would download it immediately as a file.
  So there is no GDrive or other apps involved, just a Google Sheet and an App Script.</p>
  <p>Is this somehow possible to do? I could not find anything like this.</p>