typescript declaration: module detection and namespace

Question

I am trying to write a declaration file for h3. Please see the function reference.

First, I am not sure how typescript detects the definition files.

It detects my definition, if placed on a folder /src/@types/<any filename>.d.ts, with the below content

declare module 'h3-js' {
    export type h3ToGeoBoundary = any;
    ...
}

But, I also read you can create a folder like /src/@types/h3-js/index.d.ts, but it won't detect definition if write like

export = h3;
export as namespace h3;

declare namespace h3 {
  export type h3ToGeoBoundary = () => void; // TODO: correct types
}

It doesn't matter which one works, but I am not sure how to export a namespace with first approach. With that, I get error Property 'h3ToGeoBoundary' does not exist on type 'typeof import("h3-js")'.

Please help with a minimal file, with a working export for h3ToGeoBoundary, so I can expand further.

Answer 1

Since module just exports a bunch of functions you can define them as individual exports (using your first approach):

declare module "h3-js" {
  export function h3ToGeoBoundary(): void;
}