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Question

I'm using ajax to check if a username is taken. If the username is taken it returns false to the form submit function. I'm using MySQL.

index.php

$("#register-form").submit(function(){
    var un = $("#un").val();
    $.ajax({
        type: "GET",
        url: "user_check.php",
        dataType: "html",
        data: {un: un},
        success: function(data){

        }
    });
});

user_check.php

$db = mysqli_connect("localhost","root","","webcap");
$user = $_POST['un'];
$query = mysqli_query($db,"SELECT * FROM users WHERE username='$un'");
$count = mysqli_num_rows($query);
echo $count;

How I return false to the register form submit function if data is 1 or true if it's 0? Is there an easier way to do this?

Answer 1

Use JSON. In the PHP do:

echo json_encode($count > 0);

And in the Javascript, specify type: 'json' instead of type: 'html'. Then data will be true or false.

However, since AJAX is asynchronous, you can't return a value from this.

What you need to do is prevent normal form submission in the .submit() function. Then in the success: function, check the response and submit the form if it was successful.

$("#register-form").submit(function(e){
    e.preventDefault();
    var un = $("#un").val();
    $.ajax({
        type: "GET",
        url: "user_check.php",
        dataType: "json",
        data: {un: un},
        success: function(data){
            if (data) {
                $("#register-form")[0].submit(); // really submit the form
            } else {
                alert("Username is taken");
            }
        }
    });
});