custom_html_to_head.js

<script type="text/javascript" >
AJS.toInit(function ($) {
    
    var list = AJS.$('table.confluenceTable tbody th:contains("#sum")');
    list.each(function(index, item) {
        var elem = AJS.$(item);
        var parentRow = elem.parent();
        var parentTbody = parentRow.parent();
        var column = parentRow.find('th').index(elem);
        var sum = 0;
        var totalColumns = parentRow.find('th').length;

        parentTbody.find('tr').each(function(index, row) {
            var elem = AJS.$(row);
            var td = elem.find('td');
            if (td.length > 0) {
                var value = td.eq(column).text();
                var float = parseFloat(value);
                if (!isNaN(float)) {
                    sum += float;
                }
            }
        });
        elem.text(sum);
    });
});
</script>

empty fields does not result in NaN