Live username availability checking on the registration page is the common feature in most of the website. This will notify the user whether the username is already been taken or not before submitting. To do this require AJAX. Send a request to check the username on the bases of response perform the action. In this tutorial, I show how you can check username availability using Vue.js and PHP.

1. Check Username Availability
with Vue.js and PHP
By Makitweb

2. Live username availability checking on the registration page is the common
feature in most of the website.
This will notify the user whether the username is already been taken or not
before submitting.
To do this require AJAX.
Send a request to check the username on the bases of response perform the
action.

3. Contents -
1. Table structure
2. Configuration
3. HTML
4. PHP
5. Script
6. Conclusion

4. 1. Table structure
I am using users table in the example.
CREATE TABLE `users` (
`id` int(11) NOT NULL PRIMARY KEY AUTO_INCREMENT,
`username` varchar(80) NOT NULL,
`name` varchar(80) NOT NULL,
`password` varchar(80) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

5. 2. Configuration
Create a new config.php file.

6. <?php
$host = "localhost"; /* Host name */
$user = "root"; /* User */
$password = ""; /* Password */
$dbname = "tutorial"; /* Database name */
// Create connection
$con = mysqli_connect($host, $user, $password,$dbname);
// Check connection
if (!$con) {
die("Connection failed: " . mysqli_connect_error());
}

7. 3. HTML
Create a textbox and <span> to show message.
In the textbox added v-model='username' and @keyup='checkUsername()'.
To display the message in <span> added {{responseMessage}} and
v-bind:class to change class according to isAvailable value.

8. <style >
.available{
color: green;
}
.notavailable{
color: red;
}
</style>
<div id='myapp'>
Enter username : <input type='text' v-model='username' @keyup='checkUsername()'>
<span v-bind:class="[isAvailable ? 'notavailable' : 'available']" >{{responseMessage}}</span>
</div>

9. 4. PHP
Create a ajaxfile.php file.
Check username in the users table. If record found then assign 1 to $found.
Return $found.

10. <?php
include "config.php";
$username = "";
$found = 0;
if(isset($_GET['username'])){
$username = mysqli_escape_string($con,$_GET['username']);
// Check username
$result = mysqli_query($con,"select * from users WHERE username='".$username."'");
if(mysqli_num_rows($result) > 0){
$found = 1;
}
}
echo $found;

11. 5. Script
Create 3 data variable – username, isAvaialble, and responseMessage.
Here, isAvailable is used to toggle <span> class and the responseMessage to
display a message.
Define a checkUsername method.

12. Send GET request where pass username: username. On successful callback
assign app.isAvailable = response.data.
If response.data == 0 then assign app.responseMessage = "Username is
Available." otherwise app.responseMessage = "Username is not Available.".

13. var app = new Vue({
el: '#myapp',
data: {
username: '',
isAvailable: 0,
responseMessage: ''
},
methods: {
checkUsername: function(){
var username = this.username.trim();
if(username != ''){
axios.get('ajaxfile.php', {
params: {
username: username
}
})
.then(function (response) {

14. app.isAvailable = response.data;
if(response.data == 0){
app.responseMessage = "Username is Available.";
}else{
app.responseMessage = "Username is not Available.";
}
})
.catch(function (error) {
console.log(error);
});
}else{
this.responseMessage = "";
}
}
}
})

15. 4. Conclusion
It is better to prevent the user from selecting existing username before
submitting the form.
Also, check the username availability while inserting the record.
You can view working demo here.

16. Share
For More Vue.js related tutorial
as well as other programming tutorials visit :
Makitweb.com