(function(window){
    function getEvent(){
        if(document.all){
            return window.event;
        }
        var func = getEvent.caller;
        while(func != null){
            var arg0 = func.arguments[0];
            if(arg0){
                if((arg0.constructor==Event || arg0.constructor ==MouseEvent) || (typeof(arg0)=="object" && arg0.preventDefault && arg0.stopPropagation)){
                    return arg0;
                }
            }
            func = func.caller;
        }
        return null;
    }

    function confirmClose(){
        if(window.event){
            window.event.returnValue = '您确实要退出吗？';
        }else{
            getEvent().preventDefault(); //for firefox
        }
    }

    try{
        if(!window.onbeforeunload){
            window.onbeforeunload = confirmClose;
        }
    }catch (e){}
})(window);