How to export a submodule in a Typescript library

Question

So my goal is to create a library in Typescript. My intention is to split up core parts of the library into submodules like RxJS or Angular Material.

RxJS and Angular both support imports like so:

// RxJS
import { map, filter } from 'rxjs/operators';

// Angular
import { MatButtonModule } from '@angular/material/button';

However, I am unable to replicate this myself.

My goal is to do something similar and allow you to import a class with import { foo } from 'package/bar;

I have looked at RxJS's source on Github and have tried replicating what they've done but it's not working.

The library compiles fine but when I go about importing it I always get a Cannot resolve dependency 'package/foo' error. Meanwhile doing import { test } from package (without the submodule part) works completely fine.

I've tried using paths in tsconfig to no avail. If that is the answer then I'm doing it wrong.

How do I go about doing this?

Answer 1

In order to achieve that, you can create your "sub-modules" in different directories (although they are technically part of the same module), and create an index.ts on each of those directories exporting there whatever you want to publish.

For example, I have done this in my NodeJs package Flowed, and you can for example do this:

import { FlowManager } from 'flowed/dist/engine';

Where the corresponding index.ts file is this one if you want to check.

Although in my case I put also available all the stuff from the root, so the previous line would be equivalent to:

import { FlowManager } from 'flowed';