how to know if stopped typing code example

Example 1: stopped typing jquery

var timer = null;
$('#text').keydown(function(){
       clearTimeout(timer); 
       timer = setTimeout(doStuff, 1000)
});

function doStuff() {
    alert('do stuff');
}

Example 2: call function after few sec of input type

//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
}