mod.js

var require, define;
(function () {
    var loadingMap = {};
    var factoryMap = {};
    var modulesMap = {};

    define = function (id, factory) {
        id = id.replace(/\.js$/i, '');
        factoryMap[id] = factory;

        var queue = loadingMap[id];
        if (queue) {
            for (var i = 0, n = queue.length; i < n; i++) {
                queue[i]();
            }
            delete loadingMap[id];
        }
    };

    require = function (id) {
        id = require.alias(id);

        var mod = modulesMap[id];
        if (mod) {
            return mod.exports;
        }

        var factory = factoryMap[id];
        if (!factory) {
            throw '[ModJS] Cannot find module `' + id + '`';
        }

        mod = modulesMap[id] = {
            exports: {}
        };

        var ret = (typeof factory === 'function') ? factory.apply(mod, [require, mod.exports, mod]) : factory;

        if (ret) {
            mod.exports = ret;
        }

        return mod.exports;
    };

    require.alias = function (id) {
        return id.replace(/\.js$/i, '');
    };
})(this);