Question

I am trying to only print a unique value of ‘sum’ by doing a compare at the end of the loop, but I’m seeing that every time it does a compare it has already moved on to the next element and therefore when its comparing the two values they’re always the same. Is there another way to do this?

 $(document).ready(function(){
    $.getJSON('XML.php', function(data) {
        JSON.stringify(data);
        var prevCardCode = '';

        $.each( data, function(index, element){
            var prevCardCode = element['CardCode'];

            if (!(element['CardCode'] == prevCardCode)) {

                var sum = element['payment_sum'] + '<br/>';
                $('#showdata').append(sum);
                }
                alert(element['CardCode'] + 'compare' + prevCardCode);
        });

    });
});

Answer 1

The var keyword doesn’t belong within the each in this case, and you need to move it to after the comparison.

var prevCardCode = '';
$.each(data, function(index, element) {
    if (!(element['CardCode'] == prevCardCode)) {
        var sum = element['payment_sum'] + '<br/>';
        $('#showdata').append(sum);
    }
    alert(element['CardCode'] + 'compare' + prevCardCode);
    prevCardCode = element['CardCode'];
});​

If the var is left in place before prevCardCode, it will never set the one defined outside of the $.each and will not carry over to the next iteration of $.each.