Vibration

The Vibration API causes the mobile device to vibrate in a pattern of on-off pulses.

Try running this on a mobile phone.
RESETRUNFULL
<!DOCTYPE html><html><body>
<script>
function vibrate(){
   // vibrate for 200 milliseconds
   navigator.vibrate(200);

   // vibrate for 200ms, pause for 100ms, then vibrate for 200ms again
   navigator.vibrate([200,100,200]);
}
</script>
<button onclick="vibrate()">Vibrate</button>
</body></html>