My ajax problem

JavaScript
1

I’ve been working on making an ajax save to favorite function for my project and I been ending up with this code. Please bear in mind im a noob and I’m sure it could look alot better to advice in addition to the problem is very much appreaciated.

The problem appears when I do a second click to remove it, I get issues with the php hander file. I will post the content of both

$(document).on('click', '.button6', function() {
	const tankID = <?php echo $tankID; ?>;
	const userID = <?php echo $userID; ?>;
	const favX = <?php echo $favX+1; ?>;
	
	var fx = document.getElementById('dataTxt');
	var favorite = fx.getAttribute('data-id');
	console.log("Favorite: " + favorite + "!");
	
	if (favorite == 0) {
		$.post('tanks_favorite_ajax.php', { tankID: tankID, userID: userID, favorite: favorite }, function() {
			document.getElementById("icon").src="https://www.fsd.com/icons/heartarrow.png";
			document.getElementById("dataTxt").innerHTML = "Favorited by "+ favX +" driver(s)";
			favorite = !favorite;
			var d = document.getElementById("dataTxt");
			d.setAttribute('data-id' , favorite); 
			console.log("1.Favorite is now: " + favorite + "!");
		});
	} else {
		$.post('tanks_favorite_ajax.php', { tankID: tankID, userID: userID, favorite: favorite }, function() {
			document.getElementById("icon").src="https://www.fsd.com/icons/arrow.png";
			document.getElementById("dataTxt").innerHTML = "Add to Favorites";
			favorite = !favorite;
			var d = document.getElementById("dataTxt");
			d.setAttribute('data-id' , favorite); 
			console.log("2.Favorite is now " + favorite + "!");
		});   
	}
});

<?php
include('connection.php');
include('functions.php');


if ($_SERVER['REQUEST_METHOD'] === 'POST' && isset($_POST['tankID'])) {

    $tankID = (int) $_POST['tankID'];
    $userID = (int) $_POST['userID'];
    $favorite = (int) $_POST['favorite'];

    try {
        if ($favorite == 0) {
            $stmt=$pdo->Prepare("INSERT INTO favorites (tankID, userID)
                VALUES (:tankID, :userID)");

                $stmt->execute(array(
                ':tankID' => $tankID,
                ':userID' => $userID                    
                ));
            //Add credits
            addCredit($userID, $tankID, FAVORITE, 'favorite');                
        }
        elseif ($favorite == 1) {
            $stmt=$pdo->Prepare('DELETE FROM favorites WHERE tankID=:tankID AND userID=:userID');

                $query->execute(array(
                ':tankID' => $tankID,
                ':userID' => $userID
                ));  
        }

    } catch (PDOException $e) {
        echo 'error: ' . $e->getMessage();
    }
} else {
    echo 'Invalid request';
}
?>
2

I assume you start with favorite = 0. So the first time you click it, it works, and sets favorite to true.
The second click then tries to read the favorite, and either sends a boolean or a null to the script, which dies horribly.
I suspect your problem lies here:
favorite = !favorite;
This expression will evaluate to a boolean, not an int.
!0 = true
!<any int that isnt 0 or NaN> = false.

If its meant to be an int, keep it as an int.

If you’re using an up-to-date version of PHP, check the PHP logs to find out where exactly the PHP script died; if you’re using an older one, check the response from the server for the error message.

The error message will identify the cause of your woes.

3

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