new function(){
	function rollover(){
		var targetClassName = "imgover";
		var suffix = "_on";

		var overReg = new RegExp("^(.+)(\\.[a-z]+)$");
		var outReg = new RegExp("^(.+)" + suffix + "(\\.[a-z]+)$");

		var preload = new Array();
		var images = document.getElementsByTagName("img");

		for (var i = 0, il = images.length; i < il; i++) {
			var classNames = images[i].className.split(" ");
			for(var j = 0, cl = classNames.length; j < cl; j++){
				if(classNames[j] == targetClassName){
					
					//preload
					preload[i] = new Image();
					preload[i].src = images[i].getAttribute("src").replace(overReg, "$1" + suffix + "$2");

					//mouseover
					images[i].onmouseover = function() {
						this.src = this.getAttribute("src").replace(overReg, "$1" + suffix + "$2");
					}

					//mouseout
					images[i].onmouseout = function() {
						this.src = this.getAttribute("src").replace(outReg, "$1$2");
					}
				}
			}
		}
	}
	//onload–â‘è‚ÌŠg’£
	function addLoadEvent(func) {
	var oldonload = window.onload;
		if ( typeof window.onload != 'function') {
		window.onload = func;
		} else {
			window.onload = function() {
			oldonload();
			func();
			}
		}
	}
	addLoadEvent(rollover);
	
}