var req1;
var doesNotSupport1 = true;
function check_user_name(url,c){
    //alert(url);

    if(window.XMLHttpRequest) {
       req1 = new XMLHttpRequest;
    } else if (window.ActiveXObject) {
       req1 = new ActiveXObject("Microsoft.XMLHTTP");
    }

    if(req1) {

       url=url+"?user_name="+c;

       //alert(url);
       req1.open("POST",url, true);
       req1.setRequestHeader('Content-Type','application/x-www-form-urlencoded');

       var postvalues="";
       postvalues="user_name="+c;

       //alert(postvalues);
       req1.send(postvalues);
       req1.onreadystatechange = processReqChange1;

    } else {
       alert("Please use latest version of the current browser to function properly");
       doesNotSupport1 = false;
    }
}

function processReqChange1() {

   //alert(req1.readyState);
    if(req1.readyState == 4) {
       //alert(req1.status);
       //alert(req1.responseText);

       if(req1.status == 200) {
          var aa=req1.responseText;
          var usersts;
          //alert(aa);

          if(aa == "N"){
             //alert("Username  should be valid");
             document.getElementById("usersts").innerHTML = "Username  should be valid";
             document.registration.user_name.value="";
          }
          if(aa == "-1"){
             //alert("Username  should be valid");
             document.getElementById("usersts").innerHTML = "Username  should be valid";
             document.registration.user_name.value="";
          }
          if(aa == "1"){
             //alert("Username already exists");
             document.getElementById("usersts").innerHTML = "Username already exists";
          }
          if(aa == "0"){
             //alert("Username available, you can use");
             document.getElementById("usersts").innerHTML = "Username available, you can use";
          }
      }
  }

}