$(document).ready(function(){
	$('img.swap').hover(
		function(){
			// get path, extension, then swap
			var src = $(this).attr("src");
			$(this).attr('src',getPathFromSrc(src)+$(this).attr("id")+'-on.'+getExtFromSrc(src));
			},
		function(){
			var src = $(this).attr("src");
			$(this).attr('src',getPathFromSrc(src)+$(this).attr("id")+'.'+getExtFromSrc(src));
			});
		});
	
getPathFromSrc = function(src){
	var filePos = src.lastIndexOf("/");
	var newSrc = src.substr(0,filePos+1);
	return newSrc;
	}
	
getExtFromSrc = function(src){
	var srcSplit = src.split(".");
	var ext = srcSplit[srcSplit.length-1];
	return ext;
	}