// JavaScript Document

function switcher(i) {
	var id = document.getElementById(i);
	var s = id.src;
	var type;
	var src;
	var nsrc;
	
	if (s.indexOf(".gif") >= 0) {
		type = ".gif";
	} else if (s.indexOf(".jpg") >= 0) {
		type = ".jpg";
	} else if (s.indexOf(".png") >= 0) {
		type = ".png";
	} else {
		alert("This is not an image.");
	}
	
	src = s.replace(type, "");
	
	if (src.indexOf("-on") == -1) {
		nsrc = src + "-on" + type;
	} else {
		nsrc = src.replace(/-on/, "");
		nsrc += type;
	}
	
	id.src = nsrc;
}