function getXMLRequester( ){
var RegXmlhttp=false;
    try{
        if( window.ActiveXObject ){
            for( var i = 5; i; i-- ){
                try{
                    if( i == 2 ){
RegXmlhttp = new ActiveXObject( "Microsoft.XMLHTTP" );    
                    }else{
RegXmlhttp = new ActiveXObject( "Msxml2.XMLHTTP." + i + ".0" );	
RegXmlhttp.setRequestHeader("Content-Type","text/xml");
RegXmlhttp.setRequestHeader("Content-Type","gb2312");
                 }
break;}
                catch(e){                        
                    RegXmlhttp = false;
                }
            }
        }else if( window.XMLHttpRequest ){
            RegXmlhttp = new XMLHttpRequest();
            if (RegXmlhttp.overrideMimeType) {
                RegXmlhttp.overrideMimeType('text/xml');
            }
        }
    }catch(e){
        RegXmlhttp = false;
    }
    return RegXmlhttp ;
}

 function CheckUserid()
{
 RegXmlHttp=getXMLRequester();
 
 var username=document.getElementById("username").value;
 
 RegXmlHttp.open("post","check_id.asp?username="+username,true);
 RegXmlHttp.onreadystatechange= RegStateChange;
 //loginXmlHttp.setRequestHeader("content","100");
 RegXmlHttp.send("content");
}

function RegStateChange()
{
  	if (RegXmlHttp.readyState == 4)
	{
    	document.getElementById("ShowLogin").innerHTML=RegXmlHttp.responseText;
	}
	else
	document.getElementById("ShowLogin").innerHTML="<div class='UserInputCheckTip'>正在验证中，请稍后...</div>";
}