window.onload = function(){

//RollOver
var conf = {
className : 'roll',
postfix : '_on'
};
var imgNodeList;
var node;

if(osCheck() != 1){
	imgNodeList = getElementsByClassName(conf.className);

	for (var i=0, len=imgNodeList.length; i<len; i++) {
		node = imgNodeList[i];
		node.originalSrc = node.src;
		node.rolloverSrc =
node.originalSrc.replace(/(\.gif|\.jpg|\.png)/,conf.postfix+"$1");
		preloadImage(node.rolloverSrc);
		node.onmouseover = function(){
		this.src = this.rolloverSrc;
		};
	node.onmouseout = function(){
		this.src = this.originalSrc;
		};
		}
	} else { //for mac IE
	imgNodeList = getElementsByClassNameForIE5(conf.className,conf.postfix);
	}
}


// function


//ブラウザ判別
//OS判別
function osCheck() {
       var Agent = navigator.userAgent;
       var os = 0;
       if (Agent.indexOf('Mac') != -1) {
                       os = 2;
               if (document.all) {     // Mac_IE
                       os = 1;
               }
       }
       return os;
}

//クラス名によるエレメントノード配列取得
function getElementsByClassName(name){
 var elements = [];
 var allElements = document.getElementsByTagName('*');
 for (var i=0, len=allElements.length; i<len; i++) {
   if (allElements[i].className == name){
     elements.push(allElements[i]);
   }
 }
 return elements;
}

//macie5用
function getElementsByClassNameForIE5(name,postfix2){
 var elements = new Array();
 var allElements = document.getElementsByTagName('img');
 for (var i=0, len=allElements.length; i<len; i++) {
       var str = allElements[i].getAttribute("className");
   if (str == name){
               node = allElements[i];
               node.originalSrc = node.src;
               node.rolloverSrc =
node.originalSrc.replace(/(\.gif|\.jpg|\.png)/,
postfix2+"$1");
               preloadImage(node.rolloverSrc);
               node.setAttribute("onmouseover", new Function("this.src = this.rolloverSrc;"));
               node.setAttribute("onmouseout", new Function("this.src = this.originalSrc;"));
   }
 }
}
//プリロード
preloadedImages = [];
function preloadImage(url){
	var p = preloadedImages;
	var l = p.length;
	p[l] = new Image();
	p[l].src = url;
}