JS localStorage 存储变量

 if(!window.localStorage && /MSIE/.test(navigator.userAgent)){
         if(!window.UserData) {
             window.UserData = function(file_name) {
                 if(!file_name) file_name="user_data_default";
                 var dom = document.createElement('input');
                 dom.type = "hidden";
                 dom.addBehavior ("#default#userData");
                 document.body.appendChild(dom);
                 dom.save(file_name);
                 this.file_name = file_name;
                 this.dom = dom;
                 return this;
             };

             window.UserData.prototype = {
                 setItem:function(k, v) {
                     this.dom.setAttribute(k,v);
                     this.dom.save(this.file_name);
                 },
                 getItem:function(k){
                     this.dom.load(this.file_name);
                     return this.dom.getAttribute(k);
                 },
                 removeItem:function(k){
                     this.dom.removeAttribute(k);
                     this.dom.save(this.file_name);
                 },
                 clear:function() {
                    this.dom.load(this.file_name);
                    var now = new Date();
                    now = new Date(now.getTime()-1);
                    this.dom.expires = now.toUTCString();
                    this.dom.save(this.file_name);
                 }
             };
         }
         window.localStorage= new window.UserData("local_storage");
     }