A JavaScript Modules Manager That Fits in a Tweet

ES6 does provide modules; but unless you’re using Babel you’ll have to rely on third-party libraries such as RequireJS until all major browsers support them. I use D3 everyday to visualize data about ego networks and have a small (400-500 SLOC) JavaScript codebase I need to keep organized. In the context I work in I must keep things simple as I won’t always be there to maintain the code I’m writing today. How simple a modules implementation could possibly be? It should at least be able to register modules and require a module inside another; much like Python’s import. It should also handle issues like circular dependencies (e.g. foo requires bar which requires foo) and undeclared modules. Modules should be lazily loaded, i.e. only when they are required; and requiring twice the same module shouldn’t execute it twice.