UserStoppedTyping.html

<script type="text/javascript">
	timeOfLastKeyPress = new Date().getTime() * 2; // make it in the future
	maxMillisecondsBetweenKeystrokes = 1000; 
	millisecondsBetweenCheckingForStoppage = 250;
	
	function logKeyPress(){
		timeOfLastKeyPress = new Date().getTime();
	}
	
	function userStoppedTyping(){
		if(new Date().getTime() - timeOfLastKeyPress > maxMillisecondsBetweenKeystrokes){
			alert("You stopped typing!");
			clearInterval(intervalId);
		}
	}
	
	intervalId = setInterval("userStoppedTyping()", millisecondsBetweenCheckingForStoppage);
	
</script>
<input type="text" id="field" onkeypress="logKeyPress();">