jQuery sortColumns plugin: How to sort correctly with rowspan

Question

Following this post jQuery table sort (github link: https://github.com/padolsey/jQuery-Plugins/blob/master/sortElements/jquery.sortElements.js), I am successfully sort columns,

Answer 1

Conditions for the code to work:

• Columns containing tds with rowspan must all be on the left of the table
• All the tds in these columns must have a rowspan, even if it's 1
• The groups of rows to sort are made with the rightmost of these columns (but it can easily be changed)

jsFiddle: http://jsfiddle.net/5GrAC/77/

var inverse = false;

function sortColumn(index) {
    var trs = $('#resultsTable > tbody > tr'),
        nbRowspans = trs.first().children('[rowspan]').length,
        offset = trs.first().children('[rowspan]').last().offset().left;

    var tds = trs.children('[rowspan]').each(function() {
        $(this).data('row', $(this).parent().index());
        $(this).data('column', $(this).index());
        $(this).data('offset', $(this).offset().left)
    }).each(function() {
        if($(this).data('offset') != offset)
            return;

        var rowMin = $(this).data('row'),
            rowMax = rowMin + parseInt($(this).attr('rowspan'));

        trs.slice(rowMin, rowMax).children().filter(function() {
            return $(this).index() == index + $(this).parent().children('[rowspan]').length - nbRowspans;
        }).sortElements(function(a, b) {
            a = convertToNum($(a).text());
            b = convertToNum($(b).text());

            return (
                isNaN(a) || isNaN(b) ?
                a > b : +a > +b
                ) ?
            inverse ? -1 : 1 :
            inverse ? 1 : -1;
        }, function() {
            return this.parentNode;
        });
    });

    var trs = $('#resultsTable > tbody > tr');
    tds.each(function() {
        if($(this).parent().index() != $(this).data('row'))
            $(this).insertBefore(trs.eq($(this).data('row')).children().eq($(this).data('column')));
    });

    inverse = !inverse;
}

Quick explanations:

• Finding all tds with rowspan
• Positions of these tds are saved, including left offset
• These tds are filtered by their original offset to work only with the rightmost ones
• trs related to each kept td are sorted using the wanted column
• All tds with rowspan are finally moved back to their original position if necessary

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About question 2, I will only complete bartlaarhoven's answer by saying, the code can also be written like the following:

return (
        (isNaN(a) || isNaN(b) ? a > b : +a > +b) ? 1 : -1
    ) * (inverse ? -1 : 1);

You can easily read that inverse is used to inverse the result.