jQuery prevOrAunt() - select previous siblings or parent previous siblings

jquery.prevOrAunt.js

    // find first matching prev sibling of this or of parents, within 3 levels up
    $form.prevOrAunt('.form-title,.panel-title,.panel-heading,:header', 3);

    (function($) {
      $.fn.prevOrAunt = function(search, optionalLimit) {
        // prevOrAunt(search,optionalLimit) - searches only prev and aunts [Note: aunt=parent.prev, uncle=parent.next]
        // search for matches in priority: prev siblings, parent prev siblings (repeat)
        // with optional number limit for how far up the tree to search (or false to disable limit)
        // * Modified from @Loren - http://stackoverflow.com/a/26237214/264601

        // Set a default number, attempt to user given limit
        var defaultLimit = 99; // consider performance here
        var isNumber = (Number(optionalLimit) === optionalLimit && optionalLimit % 1 === 0);
        var limit = (isNumber && optionalLimit < defaultLimit) ? optionalLimit : defaultLimit;
        // If limit is explicitly overridden with boolean=false, disable the limit, else use limit
        var useLimit = (optionalLimit === false);

        // Get the current element's siblings
        var siblings = this.prevAll(search);
        // If there's a match, we're done
        if (siblings.length) return siblings.eq(0);

        // Else traverse up another level
        var parent = this.parent();
        // If we've reached our parental limit, body or no parent, return siblings (empty jQuery object)
        if ((useLimit && limit-- && limit < 1) || parent === undefined || !parent.length || parent.get(0).tagName.toLowerCase() == 'body') return siblings;

        // Else if we've not reached our limit try, try again
        return parent.prevOrAunt(search);
      };
    })(jQuery);