<!DOCTYPE html>
<html>
<body>
<p>Click the button to wait 3 seconds, then alert "Hello".</p>
<p>After clicking away the alert box, an new alert box will appear in 3 seconds. This goes on forever...</p>
<button onclick="myFunction()">Try it</button>
<script>
var myVar;
function myFunction() {
myVar = setInterval(alertFunc, 3000);
}
function alertFunc() {
alert("Hello!");
}
</script>
</body>
</html>