/*
nav_rollover
*/
	
function navRollover(){
	
	var conf = {
		className : 'nav-off'
	}
	
var imgNodeList = getElementsByClassName(conf.className);

var node;

for (var i=0, len=imgNodeList.length; i<len; i++) {
    node = imgNodeList[i];
    node.originalSrc = node.src;
	node.rolloverSrc = node.originalSrc.match(/^(.+)_off(\.gif|\.jpg|\.png)$/,"");
	node.rolloverSrc = node.rolloverSrc[1] + ".gif";
    preloadImage(node.rolloverSrc);
    node.onmouseover = function(){
      this.src = this.rolloverSrc;
    };
    node.onmouseout = function(){
      this.src = this.originalSrc;
    }
  }
}

//get elementnode
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;
}

//preload
preloadedImages = [];
function preloadImage(url){
	var p = preloadedImages;
	var l = p.length;
	p[l] = new Image();
	p[l].src = url;
}