<!DOCTYPE html>
<html lang="en-US">
<body>
<p>Focus the input to lock your pointer.</p>
<input onfocus="myFunction()" type="text">
<p><strong>Note</strong>: Once you focus the input field, your mouse pointer will disappear. Press 'Esc' to get back the mouse pointer.</p>
<script>
var elem = document.getElementsByTagName("input")[0];
function myFunction(){
if(document.pointerLockElement == null)
elem.requestPointerLock();
}
</script> </body>
</html>