<!DOCTYPE HTML>
<html>
<head>
<script>
window.onscroll = function () {
if (window.pageYOffset == 0) {
document.getElementById('test').style.backgroundColor = "red";
}
else document.getElementById('test').style.backgroundColor = "green";
}
</script>
</head>
<body>
<div style="height:150px">
</div>
<div id="test" style="height:150px; background-color:red;">
</div>
</body>
</html>