newRegister.php

<?php
$con = mysqli_connect("localhost", "id3757086_300cem", "300cem", "id3757086_300cem");

    $name = $_POST["firstname"];
    $surname = $_POST["lastname"];
    $email = $_POST["email"];
    $username = $_POST["username"];
    $password = $_POST["password"];

    $statement = mysqli_prepare($con, "INSERT INTO user (`username`, `firstname`, `lastname`, `password`) VALUES (?, ?, ?, ?)");
    mysqli_stmt_bind_param($statement, "ssss", $username, $name, $surname, $password);
    mysqli_stmt_execute($statement);
    if($statement != false){
    $response = array();
    $response["success"] = true;  
    }
    echo json_encode($response);
	echo mysqli_connect_error()
?>