Tryit Editor v2.9

Edit This Code:
<!DOCTYPE html>
<html>
<head>
<style>div {
    background-image: url('smiley.gif');
    background-repeat: no-repeat;
    width: 400px;
    height: 400px;
    border: 1px solid #000000;
}
</style>
</head>
<body>

<button type="button" onclick="myFunction()">Position background image</button>
<br>
<div id="myDiv">
</div>

<script>
function myFunction() {
    document.getElementById("myDiv").style.backgroundPosition = "center bottom";  
}
</script>

</body>
</html>