jQuery if checkbox is checked malfunction

February 7, 2024

I’m having a bit strange problem, I have a form with a checkbox, where Jquery has to adjust values in an input field. But, when I check with console.log($('#praktijk').is(':checked')); I get a neat true or false answer, no problem there.
But when I put it in an if statement like this $('#praktijk').is(':checked') it doesn’t work, for some vague reason.
For more interpretation I’ll give the whole jscript code:

$('#praktijk').on('change', function() {
        let a = $('input[name="aantal"]').val() * $('input[name="lesprijs"]').val();
        var checked = $('#praktijk').is(':checked');
        console.log($('#praktijk').is(':checked'));
        if ($('#praktijk').is(':checked')) {
            let b = Number($('input[name="examenprijs"]').val());
        } else {
            let b = 0;
        }
        let prijs = a + b;
        $('input[name="pakketprijs"]').val(prijs);
    });

I’m really confused about this, and hope someone can help me.
Grts

>Solution :

When you declare a variable inside an if or else block using let, it is only accessible within that block. In your code, you are declaring b inside the if and else blocks, and trying to use it outside those blocks.

...
let b = 0; // Declare b outside the if-else block

if ($('#praktijk').is(':checked')) {
    b = Number($('input[name="examenprijs"]').val());
}

let prijs = a + b;
...