var xmlHttp
function check_username(str)
{
    //-------------------------------------
    var str1 =/[-a-zA-Z0-9_\.]+@[-a-zA-Z0-9]+\.[-a-zA-Z0-9\.]+/;
    var eflag = str.match(str1);
    if(eflag!=str)
    {
        //alert("Please enter a valid Email id.");
        document.getElementById("uname").innerHTML="Please enter a valid email id.";
        document.regfrm.username.select();
        document.regfrm.username.focus();
        return false;
    }
    else
    {
        document.getElementById("uname").innerHTML="";
    }
    //==========================================

    xmlHttp=GetXmlHttpObject()
    if (xmlHttp==null)
    {
        alert ("Browser does not support HTTP Request")
        return
    }     
    
    var url="chk_username.php"
    url=url+"?uname="+str
    //alert (url);
    xmlHttp.onreadystatechange=stateChangedp1

    xmlHttp.open("GET",url,true)
    xmlHttp.send(null)
}
function stateChangedp1() 
{
    
    if (xmlHttp.readyState==4 || xmlHttp.readyState=="complete")
    { 
        document.getElementById("uname").innerHTML=xmlHttp.responseText 
    } 
    else
    {
        document.getElementById("uname").innerHTML="<img src='images/common/preloader.gif' width=16 height=16 border=0 alt=''>"
    }
}
function GetXmlHttpObject()
{ 
     var objXMLHttp=null
     if (window.XMLHttpRequest)
     {
          objXMLHttp=new XMLHttpRequest()
     }
     else if (window.ActiveXObject)
     {
          objXMLHttp=new ActiveXObject("Microsoft.XMLHTTP")
     }
     return objXMLHttp
}