Check Username Availability with jQuery and AJAX

If you are allowing the user to login with their username and password then you have to make sure that every user has a unique username.

When the user goes for registration on your site check username either after form submits or check it with AJAX while entering.

In this tutorial, I am using jQuery AJAX to check username is available or not.

Contents

1. Table structure
2. Configuration
3. HTML
4. PHP
5. jQuery
6. Demo
7. Conclusion

1. Table structure

I am using users table in the tutorial example.

CREATE TABLE `users` (
  `id` int(11) NOT NULL PRIMARY KEY AUTO_INCREMENT,
  `username` varchar(80) NOT NULL,
  `fullname` varchar(80) NOT NULL,
  `password` varchar(80) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

2. Configuration

Create config.php file for database configuration.

Completed Code

<?php

$host = "localhost"; /* Host name */
$user = "root"; /* User */
$password = ""; /* Password */
$dbname = "tutorial"; /* Database name */

$con = mysqli_connect($host, $user, $password,$dbname);
// Check connection
if (!$con) {
   die("Connection failed: " . mysqli_connect_error());
}

3. HTML

Create an input field for entering username and to show availability response created <div id='uname_response'>.

Completed Code

<div>
   <input type="text" id="txt_username" name="txt_username" placeholder="Enter Username" />
   <!-- Response -->
   <div id="uname_response" ></div>
</div>

4. PHP

Create ajaxfile.php file.

Check $_POST['username'] value in users table. If username exists then return Available. message otherwise Not Available. message.

Completed Code

<?php
include "config.php";

if(isset($_POST['username'])){
   $username = mysqli_real_escape_string($con,$_POST['username']);

   $query = "select count(*) as cntUser from users where username='".$username."'";

   $result = mysqli_query($con,$query);
   $response = "<span style='color: green;'>Available.</span>";
   if(mysqli_num_rows($result)){
      $row = mysqli_fetch_array($result);

      $count = $row['cntUser'];
    
      if($count > 0){
          $response = "<span style='color: red;'>Not Available.</span>";
      }
   
   }

   echo $response;
   die;
}

5. jQuery

Send AJAX request when keyup event trigger on username field where pass the input value as data.

On a successful callback write the response in #uname_response.

Completed Code

<script>
$(document).ready(function(){

   $("#txt_username").keyup(function(){

      var username = $(this).val().trim();

      if(username != ''){

         $.ajax({
            url: 'ajaxfile.php',
            type: 'post',
            data: {username: username},
            success: function(response){

                $('#uname_response').html(response);

             }
         });
      }else{
         $("#uname_response").html("");
      }

    });

 });
</script>

6. Demo

View Demo

7. Conclusion

In this tutorial, I showed how you can check username is already taken by someone or not with AJAX.

I use keyup event to send AJAX request to check value similarly you can trigger this on any other events – keydown, change, click.

You can view the PDO version of this tutorial here.