Q:

Php ajax just want to display error message only form submit

After send my form data to php file its return if any error found. But its also return success before ajax redirect page. I want display error message only and if success, redirect another page.
ajax: 
$("#msform").submit(function(){
     $.ajax({
           type:"post",
           url:"pagesubmit.php",
           data:  $("#msform").serialize(),
           dataType : 'json',
           success: function(data){
           if ( ! data.success) {
                $(".help-block").fadeIn().html(data.error);
           } else {
                $(".help-block").fadeOut();
                $("#msform")[0].reset();
                window.location = 'http://dbsvawdez.com/' + data.success;
           }
           }
     });
});

php: 
include_once ("db.php");
global $dbh;

function check($name){
  if(!$name || strlen($name = trim($name)) == 0){
     $error ="* Username not entered";
  }
  else{
     $name = stripslashes($name);
     if(strlen($name) < 5){
        $error ="* Name below 5 characters";
     }
     else if(!preg_match("/^([0-9a-z])+$/i", $name)){
        $error ="* Name not alphanumeric";
     }
     else {
        return 1;  
     }
  } 
}

  $name = mysqli_real_escape_string($dbh, $_POST['name']);

  $thisname = strtolower($name);

  $retval = check($thisname);

  if($retval ==1){ // if no error found
   $success ='upage/userpage?user='.$_SESSION['username'].'';                           
  }

$data = array();
$data['error'] = $error;
$data['success'] = $success;
if (!empty($data)) {
    echo json_encode($data);
}

A:

Solved the problem, in this way:
Ajax:
$("#msform").submit(function(){
// collect input name
ver name = var catag=$('#name').val();
   $.ajax({
       type:"post",
       url:"pagesubmit.php",
       data:  $("#msform").serialize(),
       success: function(data){
       if ( data != 'success') {
            $(".help-block").fadeIn().html(data);
       } else {
            $(".help-block").fadeOut();
            $("#msform")[0].reset();
            window.location = 'http://dbsvawdez.com/' + name;
       }
       }
   });
});

php:
function check($name){
    if(!$name || strlen($name = trim($name)) == 0){
    echo "* Username not entered";
    }
    else{
        $name = stripslashes($name);
        if(strlen($name) < 5){
        echo "* Name below 5 characters";
        }
        else if(!preg_match("/^([0-9a-z])+$/i", $name)){
        echo "* Name not alphanumeric";
        }
        else {
        return 1;  
        }
    } 
}

$name = mysqli_real_escape_string($dbh, $_POST['name']);
$thisname = strtolower($name);
$retval = check($thisname);
if($retval ==1){ // if no error found
   echo 'success';                         
}

