菜单

document.getElementsByClassName = function(cl) {
  var retnode = [];
  var myclass = new RegExp('//b'+cl+'//b');
  var elem = this.getElementsByTagName('*');
  for (var j = 0; j < elem.length; j++) {
   var classes = elem[j].className;
   if (myclass.test(classes)) retnode.push(elem[j]);
  }
  return retnode;
 }
 
 // --- 隐藏所有
 function HideAll() {
  var items = document.getElementsByClassName("optiton");
  for (var j=0; j<items.length; j++) {
   items[j].style.display = "none";
  }
 }
 
 // --- 设置cookie
 function setCookie(sName,sValue,expireHours) {
  var cookieString = sName + "=" + escape(sValue);
  //;判断是否设置过期时间
  if (expireHours>0) {
    var date = new Date();
    date.setTime(date.getTime + expireHours * 3600 * 1000);
    cookieString = cookieString + "; expire=" + date.toGMTString();
  }
  document.cookie = cookieString;
 }
 
 //--- 获取cookie
 function getCookie(sName) {
   var aCookie = document.cookie.split("; ");
   for (var j=0; j < aCookie.length; j++){
  var aCrumb = aCookie[j].split("=");
  if (escape(sName) == aCrumb[0])
    return unescape(aCrumb[1]);
   }
   return null;
 }
 
 window.onload = function() {
  var show_item = "opt_1";
  if (getCookie("show_item") != null) {
    show_item= "opt_" + getCookie("show_item");
  }
  document.getElementById(show_item).style.display = "block";
  var items = document.getElementsByClassName("title");
  for (var j=0; j<items.length; j++) {
   items[j].onclick = function() {
    var o = document.getElementById("opt_" + this.name);
    if (o.style.display != "block") {
     HideAll();
     o.style.display = "block";
     setCookie("show_item",this.name);
    }
    else {
     o.style.display = "none";
    }
   }
  }
 }