一直没有解决的问题？高手指点 每天看都没有人回答 好可怜

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"  ><head>
<title>选取页面</title>
    <script type="text/javascript">
    <!--
    var xmlhttp;
    
    function createHTTP()
    {
        if (window.ActiveXObject)
        {
            xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
        }
        else if (window.XMLHttpRequest)
        {
            xmlhttp = new XMLHttpRequest();
        }
    }
    
    function GetData(value)
    {
        createHTTP();
        xmlhttp.onreadystatechange = StateChange;
        xmlhttp.open("GET", value, false);

        xmlhttp.send();
    }
    
    function StateChange()
    {
        if (xmlhttp.readystate == 4)
        {
            if (xmlhttp.status == 200)
            {
document.getElementById('frame1').contentWindow.document.charset="utf-8";   
                document.getElementById('frame1').contentWindow.document.body.innerHTML =byte2str(xmlhttp.responseBody)
                document.getElementById('frame1').contentWindow.document.onmouseup = ShowSelection;
            }
        }
    }
    
    function ShowSelection()
    {
        var selection = document.getElementById('frame1').contentWindow.document.selection;
        document.getElementById('txtShow').value+= selection.createRange().text;
    }
    
function byte2str(data){  
    var glbEncode = [];  
    gb2utf8_data = data;  
    execScript("gb2utf8_data = MidB(gb2utf8_data, 1)", "VBScript");  
    var t=escape(gb2utf8_data).replace(/%u/g,"").replace(/(....{2})(....{2})/g,"%$2%$1").replace(/%([A-Z].)%(....{2})/g,"@$1$2");  
    t=t.split("@");  
    var i=0,j=t.length,k;  
    while(++i<j){  
        k=t[i].substring(0,4);  
        if(!glbEncode[k]) {  
            gb2utf8_char = eval("0x"+k);  
            execScript("gb2utf8_char = Chr(gb2utf8_char)", "VBScript");  
            glbEncode[k]=escape(gb2utf8_char).substring(1,6);  
        }  
        t[i]=glbEncode[k]+t[i].substring(4);  
    }  
    gb2utf8_data = gb2utf8_char = null;  
    return unescape(t.join("%"));  
}  
    //-->
    </script>
    
<meta http-equiv="Content-Type" content="text/html; charset=gb2312"><style type="text/css">
<!--
body {
margin-left: 0px;
margin-top: 0px;
}
-->
</style></head>
<body >
<table width="200" border="0" align="center" bgcolor="#009900">
      <tr>
        <td><div align="center">
              <strong>输入页面地址：</strong>          
          <input name="t" type="text" size="50" maxlength="100" id="t" value="http://www.google.cn"/>
          <input type="button" name="Submit" accesskey="enter" value="打开页面" onclick="GetData(document.getElementById('t').value)" />
        </div></td>
      </tr>
      <tr>
        <td><textarea name="txtShow" cols="120" rows="10"  id="txtShow"></textarea></td>
      </tr>
      <tr>
        <td><iframe width="100%" height="800" id="frame1" >
        </iframe></td>
      </tr>
    </table>
  
</body>
</html>
显示的文字还是乱码
希望高手给我解决
在此谢过了