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"); 
    }