去除移动端alert/confirm的网址(url)

移动端的alert、confirm都会显示来源的url，影响体验
下面的代码将alert和confirm重写了一遍，可去除url
参考了网上代码，完善了confirm不同状态跳转

示例代码：

     <!DOCTYPE html>  
    <html>  
    <head>  
    <meta charset="utf-8">  
    <title>文档标题</title>  
    </head>  
       
    <body>  
    <script type="text/javascript">  
    /*remove url of alert/confirm*/    
    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);    
        }    
    }   
      
    var r=confirm("Press a button");  
    if (r==true)  
    {  
        document.write("You pressed OK!");  
    }  
    else  
    {  
        document.write("You pressed Cancel!");  
    }  
    </script>  
      
    </body>  
       
    </html>