If you have a Google account, you can save this code to your Google Drive.
Google will ask you to confirm Google Drive access.
Save file as:
If you have saved a file to Google Drive, you can open it here:
Click "Try it". Wait 3 seconds. Your page will alert "Hello".
When you close the alert box, an new alert box will appear in 3 seconds.
This will go on forever, until you close the window.