<!DOCTYPE html>
<html>
<head><script type="text/javascript">
// var intervalID = window.setInterval(func, delay[, param1, param2, ...]);
// var intervalID = window.setInterval(code, delay);
var intervalID;
function setTrafficLightColor() {
intervalID = setInterval(changeTextColor, 1000);
}
function changeTextColor() {
var tl = document.getElementById("id-traffic-light");
tl.style.color = tl.style.color == "red" ? "green" : "red";
}
function stop() {
clearInterval(intervalID);
}
</script></head>
<body onload="setTrafficLightColor();">
<div id="id-traffic-light">
<p>Traffic Light</p>
</div>
<button onclick="stop();">Stop Interval</button>
</body>
</html>
