How one piece of functionality could be created out of many files.

oneOutOfMany.js

/*
Define a library called foo that has a parse and render
functionality, and a utility function called escape.
*/

/** foo.js **/
//If wanting a global, declare it here
var foo;

//Assemble foo from parts
define([
    //exports is special, it creates an empty object
    //for foo immediately.
    'exports',

    //loads parse.js as a sibling to foo.js
    './parse', 
    './compile',
    './util/escape'
], function (exports) {
    //Optionally create a global object
    //for apps that just want to use 
    //<script src="foo.js"> and use
    //a global "foo" object to interact.
    foo = exports;
});

/** foo/parse.js **/
//Asking for './foo' will get the exports object
//created in foo.js.
define(['./foo'], function(foo) {
    foo.parse = function () {};
});

/** foo/render.js **/
define(['./foo'], function(foo) {
    foo.render = function () {};
});

/** foo/util/escape.js **/
define(['../foo'], function(foo) {
    foo.escape = function () {};
});

/** RequireJS optimizer can turn the above into one file. **/