Ajax function firing multiple times when user scrolls to bottom

Question

This is most likely a duplicate and yes, I have seen them here and here . My question is fairly similar to the second one.

The second link suggests that to fix this problem, one must do something like this:

function loadMoreResults() {
  if (flag) return;
  flag = true;
[...]
  flag = false;
}

I have tried installing such logic within my actual code but all it does is give syntax errors no matter if the ()'s and {}'s have been opened and closed correctly. Perhaps I have done it wrong.

$(document).ready(

    function loadAll (param) {
        if (param < 0) {
            return;
        } else if (isNaN(param)) {
            param = param.responseText;
        } else if (!isNaN(param)) {
        }

        $.ajax({
            url: '../login/functionLogin/functions.php',
            type: 'POST',
            dataType: 'JSON',
            data: {task: "load", next_id: param},
            success: function(data) {
                next_id = data.next_id;
                $.each(results, function(i, attr) {
                     //Do whatever and return next_id
                    }       
                })

            }
        });

        //Since the next_id is within the function, I do not have to make it global.

        $(window).scroll(function () { //If user scrolls to bottom, fire anything inside
                if ($(window).scrollTop() >= $(document).height() - $(window).height()) {

                    loadAll(next_id).die(); //Firing twice or even thrice

        }
    })

});

The question: How can I stop my current script from firing twice? Is the structure of this script good? [I strongly feel like it is very bad designed and the one causing this problem]

I can elaborate more. I tried my best wording this question.

Answer 1

It seems that you answered your own question ! add a variable and check if it is not defined then do the processing, if already set then don't do anything.

    $(window).scroll(function () { //If user scrolls to bottom, fire anything inside
            if ($(window).scrollTop() >= $(document).height() - $(window).height()) {
                if (typeof flag != 'undefined' && flag) return;
                loadAll(next_id); // .die(); // what is the die();  ??? //Firing twice or even thrice
                flag = true;

      }
    })