jQuery custom selector :count

jquery.custom-selectors.count.js

/* jquery.custom-selectors.count.js
 * 
 * custom selector for finding elements that have a certain child/descendant count
 *
 * Usage:  $("td:count(div, 3)")    - all <td> that have 3 <div> as direct children
 *         $("td:countAll(div, 3)") - all <td> that have 3 <div> as descendants
 */

jQuery.extend(jQuery.expr[':'], (
    function () {
        var metaParser = function(meta) {
            var args = meta[3],
                lastComma = args.lastIndexOf(",");
            return {
                selector: args.slice(0, lastComma), 
                count: parseInt(args.slice(lastComma + 1), 10)
            };
        };
        return {
            count: function(element, index, meta) {
                var args = metaParser(meta);
                return $(element).children(args.selector).length === args.count;
            },
            countAll: function(element, index, meta) {
                var args = metaParser(meta);
                return $.find(args.selector, element).length === args.count;
            }
        };
    })()
);