how to change a class in php tags ?

[EarlyDude]

I am trying to change the class of a button if a conditon is not met (   if(strlen($username) < 5)    ) this is my code :

 

 

 

 

<?php $buttonClass = 'btn btn-primary'; ?>

 

<?php

 

 

if(isset($_POST['name']) && $_POST['name'] != ""){

 

    $username = preg_replace('#[^a-z0-9]#i', '', $_POST['name']);

    $quer = "SELECT * FROM users WHERE username = '$username'";

    $resu = mysqli_query($dbc,$quer);

    $check = mysqli_num_rows($resu);

    if(strlen($username) < 5){

      echo '<span  class = "glyphicon glyphicon-remove" style = "color:red"> More then 4 caracters </span>';

      

      $buttonClass = 'btn btn-primary disabled';

   exit();

      

    }

 

    elseif(is_numeric($username[0])){

      echo '<span  class = "glyphicon glyphicon-remove" style = "color:red"> First character mst be a letter </span>';

      $buttonClass = 'btn btn-primary disabled';

      exit();

    }

 

 

 

    elseif($check < 1){

      echo '<span class = "glyphicon glyphicon-ok" style = "color:green"> ' . $username . ' is available</span>';

      

    }else{

 

      echo '<span  class = "glyphicon glyphicon-remove" style = "color:red"> This username is already taken </span>';

      $buttonClass = 'btn btn-primary disabled';

      exit();

    }

 

 

}

 

 

?>

 

<script type="text/javascript" language = "javascript">

 

function checkUsername () {

  var status = document.getElementById("usernamestatus");

  var u = document.getElementById("username").value;

  if(u != "")

  {

    

    status.innerHTML = 'Se verifica...';

    var hr = new XMLHttpRequest();

    hr.open("POST","register.php",true);

    hr.setRequestHeader("Content-type", "application/x-www-form-urlencoded");

    hr.onreadystatechange = function(){

        if(hr.readyState == 4 && hr.status == 200){

 

          status.innerHTML = hr.responseText;

 

        }

      }

 

 

  var v = "name="+u;

  hr.send(v);

       

 

 

 }

 

}

 

</script>

 

 

 

AND this is my html(under the php and the script)

 

<div class="form-group">

      <label for="username" class="col-lg-2 control-label">Username:</label>

      <div class="col-lg-10">

        <input type="text" name = "username" class="form-control" id="username" onkeyup="checkUsername()">

      

      <br><div class = "userspan">

             <span style = "font-size:15px"id = "usernamestatus"></span>

          </div>

</div>

    </div>

    <button type="reset" class="btn btn-default">Cancel</button>

        <button type="submit" class="<?php echo $buttonClass ?>" id = "submit" >Submit</button>

 

 

Now i know there is something to do with the exit() function but if i don't put it then the html apears on the page twice,how can i stop that from happening ? Please can someone help ?

 

[EarlyDude]

i found out the answer,can this post be delleted please ?