HTML navigation with keyboard

keypower.js

(function ($) {
    var keyNames = {
        alt: 18, backspace: 8, capslock: 20, ctrl: 17, 'delete': 46,
        down: 40, end: 35, enter: 13, esc: 27, home: 36, insert: 45,
        left: 37, menu: 93, numlock: 144, numpad_add: 107, numpad_decimal: 110,
        numpad_divide: 111, numpad_enter: 108, numpad_multiply: 106,
        numpad_subtract: 109, pagedown: 34, pageup: 33, pause: 19, right: 39,
        scrolllock: 145, shift: 16, space: 32, tab: 9, up: 38, windows: 91
    };

    var navegableItems = function () {
        return $('a:visible, :input:visible, [tabindex]:visible', $(this).parents('.navegable')).filter(function () {
            if (!$(this).parents('a:visible, [tabindex]:visible').length) return true;
        });
    };

    $.fn.keypower = function (keyPressed, callback) {
        var behaviour = function (e) {
            var eventKey = e.which;
            var target = e.target;

            if ((keyNames[keyPressed] || keyPressed) === eventKey) {
                if (callback) return callback.call(target);
                else e.stopPropagation();
            };
        };

        if (!keyPressed && !callback) keysinit.call(this);
            
        $(this).unbind('keydown.' + keyPressed);
        $(this).bind('keydown.' + keyPressed, behaviour);

        return this;
    };

    var keysinit = function () {
        $(this).keypower('up', function () {
            $(this).neighbors(navegableItems.call(this)).previous.focus();
            return false;
            
        }).keypower('down', function () {
            $(this).neighbors(navegableItems.call(this)).next.focus();
            return false;
            
        }).keypower('enter', function () {
            if ($(this).is(":input:not(:submit):not(:button)")) {
                $(this).neighbors(navegableItems.call(this)).next.focus().select();
                return false;
            }
        });
    };
})(jQuery);

$.fn.neighbors = function (navegableItems) {
    var index = $.inArray(this.get(0), navegableItems);

    var previous = navegableItems.eq(index - 1);
    var next = (navegableItems.length <= index + 1) ?
        			navegableItems.eq(0) :
                    navegableItems.eq(index + 1);

    return { previous: previous, next: next };
};