去除alert/confirm所带的网址

var wAlert = window.alert;    
        window.alert = function (message) {    
            try {    
                var iframe = document.createElement("IFRAME");    
                iframe.style.display = "none";    
                iframe.setAttribute("src", 'data:text/plain,');    
                document.documentElement.appendChild(iframe);    
                var alertFrame = window.frames[0];    
                var iwindow = alertFrame.window;    
                if (iwindow == undefined) {    
                    iwindow = alertFrame.contentWindow;    
                }    
                iwindow.alert(message);    
                iframe.parentNode.removeChild(iframe);    
            }    
            catch (exc) {    
                return wAlert(message);    
            }    
        }    
        var wConfirm = window.confirm;    
        window.confirm = function (message) {    
            try {    
                var iframe = document.createElement("IFRAME");    
                iframe.style.display = "none";    
                iframe.setAttribute("src", 'data:text/plain,');    
                document.documentElement.appendChild(iframe);    
                var alertFrame = window.frames[0];    
                var iwindow = alertFrame.window;    
                if (iwindow == undefined) {    
                    iwindow = alertFrame.contentWindow;    
                }    
                var result=iwindow.confirm(message);    
                iframe.parentNode.removeChild(iframe);    
                return result;  
            }    
            catch (exc) {    
                return wConfirm(message);    
            }    
        }