function PageUnloader() {    //當用戶退出時是否需要拋出一個提示    this.UnloadTips = true;    var _this = this;    this.Init = function() {        //當用戶退出時拋出一個提示        window.onbeforeunload = function(e) { e = window.event || e; return _this.body_onbeforeunload(e); };        };        //Unload事件, 當用戶退出時是否需要拋出一個提示    this.body_onbeforeunload = function(e) {        if (this.UnloadTips) {            return "Your project has not been saved and any changes made will be lost!";        }    };}var oUnloader = new PageUnloader();