(function(){
 	function rollover(){
		var imgList = document.getElementsByTagName("img");
		var targetImg = [];
		for(var i=0,len=imgList.length;i<len;i++){
			if(imgList.item(i).className == "image_hover"){
				targetImg.push(imgList.item(i));
			}
		}
		if(targetImg.length == 0) return;
		for(var i=0,len=targetImg.length;i<len;i++){
		/*
			var flg = targetImg[i].src.lastIndexOf("_off");
			var extension = targetImg[i].src.substring(flg);
			var a_extension = "_on" + extension;
			var that = targetImg[i];
		*/
			(function(_targetImg){
				_targetImg.onmouseover = function(){
					_targetImg.src = _targetImg.src.replace("_off","_on");
					//_targetImg.setAttribute("src",_targetImg.src.replace(extension,a_extension));
				};
				_targetImg.onmouseout = function(){
					_targetImg.src = _targetImg.src.replace("_on","_off");
					//_targetImg.setAttribute("src",_targetImg.src.replace(a_extension,extension));
				};
			})(targetImg[i])
		}
	}
	window.onload = function(){
		rollover();
	}
})()