CommonJS Module simple implemention

require.js

/**
 * Define a module along with a payload
 * @param module a name for the payload
 * @param payload a function to call with (require, exports, module) params
 */
 
(function() {
    
var global = (function() {
    return this;
})();

if (typeof requirejs !== "undefined")
    return;

var _define = function(module, deps, payload) {
    if (typeof module !== 'string') {
        if (_define.original)
            _define.original.apply(window, arguments);
        else {
            console.error('dropping module because define wasn\'t a string.');
            console.trace();
        }
        return;
    }

    if (arguments.length == 2)
        payload = deps;

    if (!_define.modules)
        _define.modules = {};
        
    _define.modules[module] = payload;
};
if (global.define)
    _define.original = global.define;
    
global.define = _define;


/**
 * Get at functionality define()ed using the function above
 */
var _require = function(parentId, module, callback) {
    if (Object.prototype.toString.call(module) === "[object Array]") {
        var params = [];
        for (var i = 0, l = module.length; i < l; ++i) {
            var dep = lookup(parentId, module[i]);
            if (!dep && _require.original)
                return _require.original.apply(window, arguments);
            params.push(dep);
        }
        if (callback) {
            callback.apply(null, params);
        }
    }
    else if (typeof module === 'string') {
        var payload = lookup(parentId, module);
        if (!payload && _require.original)
            return _require.original.apply(window, arguments);
        
        if (callback) {
            callback();
        }
    
        return payload;
    }
    else {
        if (_require.original)
            return _require.original.apply(window, arguments);
    }
};

if (global.require)
    _require.original = global.require;
    
global.require = function(module, callback) {
    return _require("", module, callback);
};

global.require.packaged = true;

var normalizeModule = function(parentId, moduleName) {
    // normalize plugin requires
    if (moduleName.indexOf("!") !== -1) {
        var chunks = moduleName.split("!");
        return normalizeModule(parentId, chunks[0]) + "!" + normalizeModule(parentId, chunks[1]);
    }
    // normalize relative requires
    if (moduleName.charAt(0) == ".") {
        var base = parentId.split("/").slice(0, -1).join("/");
        moduleName = base + "/" + moduleName;
        
        while(moduleName.indexOf(".") !== -1 && previous != moduleName) {
            var previous = moduleName;
            moduleName = moduleName.replace(/\/\.\//, "/").replace(/[^\/]+\/\.\.\//, "");
        }
    }
    
    return moduleName;
};


/**
 * Internal function to lookup moduleNames and resolve them by calling the
 * definition function if needed.
 */
var lookup = function(parentId, moduleName) {

    moduleName = normalizeModule(parentId, moduleName);

    var module = _define.modules[moduleName];
    if (!module) {
        return null;
    }

    if (typeof module === 'function') {
        var exports = {};
        var mod = {
            id: moduleName, 
            uri: '',
            exports: exports
        };
        
        var req = function(module, callback) {
            return _require(moduleName, module, callback);
        };
        
        var returnValue = module(req, exports, mod);
        exports = returnValue || mod.exports;
            
        // cache the resulting module object for next time
        _define.modules[moduleName] = exports;
        return exports;
    }

    return module;
};

})();