how to vibrate phone using javascript
// vibrate device for 300 milliseconds
window.navigator.vibrate(300);
// vibrate for 300 milliseconds
// then wait for 100 milliseconds
// vibrate again for 200 milliseconds
window.navigator.vibrate([300, 100, 200]);
// cancel out ongoing vibration
window.navigator.vibrate(0);
//https://usefulangle.com/post/185/javascript-vibrate-device