ES6 module import doesn't require relative identifier to load relative file

[jbrantly]

This could be by design but it just surprised me and I wanted to verify behavior.

With CommonJS, relative modules must start with "./" or "../", otherwise it's considered to be a top-level module.

As near as I can tell with ES6, module naming is "loader implementation specific". It would seem that TypeScript's implementation does not require "./" or "../" to reference a relative file. For example:

// dep.ts

export class Test {}

// app.ts

import { Test } from 'dep';

Is this intended? I'm not super familiar with prevailing ES6 module loading standards, but I put together a quick test using SystemJS. It also does not allow referencing a relative module without './' or '../' unless that module happens to be in the preconfigured "base" URL. In other words, the above example would probably work out of the box, but the following would not:

// components/helper.ts

export function someHelper();

// components/dep.ts

import * as helper from 'helper'; // this line would error at runtime in SystemJS, but not in TS

export class Test {}

// app.ts

import { Test } from 'components/dep';

My understanding is that work is being made in #2338 and things like #4154 which may help to alleviate issues like this since it would allow TypeScript to be aware of that "loader-implementation specific" part. In the meantime, is the current default correct? As an alternative, perhaps it would make sense for ES6 imports to not have this behavior if --module commonjs is set, since this clearly does not follow the CJS spec.

[mhegazy]

@jbrantly the current module resolution logic is a bit weird :D. if you are loafing module "helpers", the compiler will look for a file called "helpers.d.ts" in the current directory, then will keep walking up the directory tree searching for "helpers.d.ts"...

obviously this is not correct, hence #2338. @vladima is actively working on this now. so hopefully we have some relief soon.

but just to make sure i understood correctly, you want it to be an error to not use "./" or "../" with relative modules?

[jbrantly]

but just to make sure i understood correctly, you want it to be an error to not use "./" or "../" with relative modules?

In short, yes.

[mhegazy]

good.. it should be soon :D

[jbrantly]

Thanks for confirmation of intended behavior 👍