Question

So I am trying to sort an un-ordered list by the data-id attribute of a child element within each <li>. How do I target this element to sort by its value?

Here is my current code:

    $("#sort_popularity").live("click", function() {
        var listitems = list.children('li').get();

        listitems.sort(function(a, b) {
            var compA = $(a).("#subject_popularity");
            var compB = $(b).("#subject_popularity");
            return compA < compB;
        });

        $.each(listitems, function(index, item) {
            list.append(item); // (List is defined elsewhere in my code)
        });
    });

HTML:

<a href="#" id="sort_popularity">Sort</a>

<ul>
    <li><span id="popularity" data-id="10">10</li>
    <li><span id="popularity" data-id="20">20</li>
    <li><span id="popularity" data-id="5">5</li>
</ul>

Answer 1

// for ASC.
var lis = $('ul li');

lis.sort(function(a, b) {
    return parseInt($('span', a).data('id'), 10) > parseInt( $('span', b).data('id'), 10);
});

$('ul').html(lis);

AND

// for DESC.
var lis = $('ul li');

lis.sort(function(a, b) {
    return parseInt( $('span', a).data('id'), 10) < parseInt( $('span', b).data('id'), 10);
});

$('ul').html(lis);

Note

change ids of spans, no same id for multiple span and close your span tag(may be typos).