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, however it does not work in the case of rowspan: For example, case like this

 Grape      3,096,671M
            1,642,721M
 Apple      2,602,750M
            3,122,020M

When I click on the second column, it try to sort

 Apple      2,602,750M
            1,642,721M
 Grape      3,096,671M
            3,122,020M

which as you can see is not correct, please any jQuery guru help me fix this problem. Here is my code

var inverse = false;
function sortColumn(index){
    index = index + 1;
    var table = jQuery('#resultsTable');
    table.find('td').filter(function(){
        return jQuery(this).index() == index;
    }).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;
    });
    inverse = !inverse;
}
function convertToNum(str){
    if(isNaN(str)){
        var holder = "";
        for(i=0; i<str.length; i++){                                
            if(!isNaN(str.charAt(i))){
                holder += str.charAt(i);
            }
        }
        return holder;
    }else{
        return str;
    }
}

Question:

1.How do I sort this with rowspan. THE NUMBER OF ROWSPAN IS NOT ALWAYS THE SAME. The above example both Grape and Apple have rowspan of 2, but this is not always the case.

2.Can any explain this syntax:

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

So I can see that if either a or b is not a number, then do string comparison otherwise do number comparison, but I dont understand the

inverse ? -1 : 1 :
inverse ? 1 : -1;