ajax checking username onblur - php

Question

here is the case guys, I'm trying to check username on onblur event with help of ajax , which is checking username availability in mysql database.
here is ajax script =>
document.getElementById("r_username").onblur = function(){
var http = false;
var error = document.getElementById("error_username");
var numLetter = /^[a-zA-Z-0-9]+$/;
if (this.value==""){
error.innerHTML = "Empty Field !!!";
error.style.display = "inline";
} else {
if (this.value.match(numLetter)){
if (window.XMLHttpRequest){
http = new XMLHttpRequest();
} else {
http = new ActiveXObject("Microsoft.XMLHTTP");
}
if (http){
http.open("POST","./config/AjaxUsernameEmail.php",true);
http.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
http.onreadystatechange = function(){
if (http.readyState==4 && http.status==200){
}
};
http.send("r_username=" + document.getElementById("r_username").value);
}
error.innerHTML = "";
error.style.display = "none";
} else {
error.innerHTML = "Invalid Number !!!";
error.style.display = "inline";
}
}
};
ajax working successfully and .php file too which script is below =>
class Checking{
private $con,$query,$flag;
public function __construct($con,$query){
$this->con = $con;
$this->query = $query;
}
public function func(){
if (mysqli_connect_errno()==0){
if ($result = mysqli_query($this->con,$this->query)){
if ($data = mysqli_fetch_assoc($result)){
return $this->flag = true;
} else {
return $this->flag = false;
}
}
}
}
}
if (isset($_POST['r_username'])){
$check = new Checking($connection,"SELECT username FROM users WHERE username='" . $_POST['r_username'] . "'");
} else {
header("Location: http://" . $mysql->host . "/index.php");
}
everything is working just fine , but here is the problem , i want to connect somehow this files , I mean that I want to know in .js file when username is matching in database and when not , because I want to do more action in .js file , but I can not set "flag" (variable which will help me for that).
Any ideas ? thanks :)))
In more details , .js file is in registration.php file , and how you can see guys .js file is invoking with ajax AjaxUsernameEmail.php file, so I want to do somehow to know when username is matching and when not , because I want in registration.php file to do more actions (notifications) during matching

Answer 1

The code could be a bit more like so:
$return = 'fail';
class Checking {
public function __construct($con, $query)
{
$this->con = $con;
$this->query = $query;
self::func()
}
public function func()
{
$result = 'ok';
if (mysqli_connect_errno()==0){
if ($result = mysqli_query($this->con,$this->query)){
$result = mysqli_num_rows($result) > 0? 'user_exists' : 'user_doesnt_exist';
}
}
return $result;
}
}
if( $_POST['r_username'] ){
$desired = mysqli_real_escape_string($_POST['r_username']);
$return = new Checking($connection,"SELECT username FROM users WHERE username='$desired'");
}
echo $return;
Also, you should be worried about escaping user input, and may want to look into jQuery for your ajax stuff.
The checking on the client side, should go something like this:
if (http.readyState==4 && http.status==200){
switch (http.responseText){
case 'fail':
//the username was not provided
break;
case 'user_exists':
//the username already exists
break;
case 'user_doesnt_exist':
//the username was not found on the database, continue
break;
}
}

Answer 2

For ajax request you must not return the value but print or echo it. Try
if ($data = mysqli_fetch_assoc($result)){
echo $this->flag = true; exit;
} else {
echo $this->flag = false; exit;
}
Evaluationg response:
if ( http.readyState == 4 && http.status == 200 ) {
switch ( http.responseText ) {
case 1: //user name taken, diplay error message
break;
case 0: //user name available, no action required
break;
}
}