rip

<!DOCTYPE html>
<html>
<title>Traffic Light Changer</title>
<a href="javascript:changeLight('mainImage')"><img src="green.jpg"></a>

<script>
var mainImage = document.getElementById("mainImage");

var imageList = ["green.jpg","yellow.jpg","redyellow.jpg","red.jpg"]
var imageIndex = 0;

function changeLight() {
	mainImage.setAttribute("src",imageList[imageIndex]
	imageIndex = (imageIndex + 1)
}

</script>

<button onclick "changeLight">Change Light</button>
<body>
</body>
</html>