How to Call ajax when user finished typing jQuery , AJAX

<script>
/* setup before functions */
var typingTimer;                /* timer identifier */
var doneTypingInterval = 5000;  /* time in ms, 5 second for example */
var $input = $('#myInput');

/* on keyup, start the countdown */
$input.on('keyup', function () {
  clearTimeout(typingTimer);
  typingTimer = setTimeout(doneTyping, doneTypingInterval);
});

/* on keydown, clear the countdown */
$input.on('keydown', function () {
  clearTimeout(typingTimer);
});

/* user is "finished typing," do something */
function doneTyping () {
  /*do something
}
</script>