I am so new to javascript that the following is the first script that I have ever written myself (that I didn't just copy/paste from someone else).

Not surprisingly I cant get it to work. Can anyone offer some suggestions?

The idea here is that I have a table full of thumbnails that when hovered load a new image in another box beside the thumbnails (called photobox).


Code:
<script type="text/javascript">
		var photobox;
		
		function loadImageInPhotobox()
		{
			var id = thumb.id;
			var filename="images/" + id + "_full.jpg";
			photobox.style.background="url(" + filename + ")";
		}
		
		function init()
		{
			photobox=document.getElementById("photobox");
			
			var thumb = document.getElementByClass("thumbnail");
			thumb.onmouseover=loadImageInPhotobox();
		}
		onload=init; 
	</script>