<!DOCTYPE html>
<html>
<body>
<p>Click the first button to alert "Hello" after waiting 5 seconds.</p>
<p>Click the second button to prevent the first function to execute. (You must click it before the 5 seconds are up.)</p>
<button onclick="myFunction()">Try it</button>
<button onclick="myStopFunction()">Stop the alert</button>
<script>
var myVar;
function tt() {
window.alert("Hello");
}
function myFunction() {
myVar = setTimeout(tt, 5000);
}
function myStopFunction() {
clearTimeout(myVar);
}
</script>
</body>
</html>