<input type='text' name='text1' onkeyup='exec(this.value);'/>
<script>
exec = function(textdata) { alert(textdata); }
</script>

<input type='text' name='text1' onkeyup='exec(this.value);'/>
<script>

var timer; //This needs to be a global variable

exec = function(textData){

  clearTimeout(timer);

  timer = setTimeout(function(){ alert(textData) }, 2000);
}
</script>