<!DOCTYPE html>var c=0;var t;var timer_is_on=0;function timedCount(){document.getElementById('txt').value=c;c=c+1;t=setTimeout(function(){timedCount()},1000);}function doTimer(){if (!timer_is_on){timer_is_on=1;timedCount();}}function stopCount(){clearTimeout(t);timer_is_on=0;}type="button" value="Start count!" onclick="doTimer()"type="text" id="txt"type="button" value="Stop count!" onclick="stopCount()"