Simple key-combo detector. Uses jQuery

jquery.combobreaker.js

(function($) {

    $.fn.comboBreaker = function(options) {
        var index = 0, timeout = null, dfd = $.Deferred();
            options = $.extend({}, $.fn.comboBreaker.defaults, options);

        if (! options.combo) {
            throw new Error("combo not set");
        }

        $(this).keyup( function(e) {
            // for some reason, jQuery always gives us back the upper-case
            // ASCII value for e.which, which brings us to:
            var expected = options.keyMap[options.combo[index]] ||
                options.combo[index].toUpperCase().charCodeAt();
            if (e.which === expected) {
                clearTimeout(timeout);

                if (index === options.combo.length -1) {
                    dfd.resolve();
                    index = 0;

                    return;
                }

                index++;
                timeout = setTimeout(function() {
                    index = 0;
                }, options.resetTime);
            }
        });
        return dfd.promise();
    };

    $.fn.comboBreaker.defaults = {
        resetTime : 1000,
        keyMap : {
            'enter':    13,
            'esc':      27,
            'left':     37,
            'up':       38,
            'right':    39,
            'down':     40
        }
    };
})(jQuery);

test.js

$(document).comboBreaker({
    combo : ["up", "up", "down", "down", "left", "right", "left", "right", "b", "a", "enter"]
}).done(
    function () {
        console.log('CCCCCOMBO BREAKER!');
    }
);