How to export typings from a node package

[verheyenkoen]

I'm converting a node API wrapper package (not published on NPM, I just install it using the GitHub path but that doesn't matter I guess) for Aleph X-services to Typescript. I wrote a file aleph.d.ts with typings for what the API returns (it responds XML and xml2js converts it to JS objects, which I need types for).

The typings file looks like this:

export declare namespace Aleph {
  type BorrowerInfoResponse {
    // ...
  }

  // ...
}

Whenever I build that with tsup (with the --dst flag), tsup removes the export keyword in the "dist/index.d.ts" file. The rest of the types is output as is to my dist folder, but not the export keyword, which makes it impossible to import these types from consumer projects. When I import the functions from same package in a Typescript file of a consumer project, types are inferred correctly (I can click to the definition), but in one case it is not, and I have to cast it manually which cannot be done if the Aleph namespace is not exported correctly.

I found, I can just rename the file aleph.d.ts to aleph.ts and add export * from './aleph' to my index.ts file and everything works but that doesn't feel right as it contains only typings for the API response structure.

Am I doing something wrong or is this a bug in tsup?

[baga89]

I'm facing a similar issue. I'm bundling a third-party package that contains a file with several enums, each prefixed with the export keyword. However, after the bundling process is complete, all the enums are missing the export keyword.

[benjick]

Any solution for this yet?

My file looks like this:

import createClient, { ClientOptions } from "openapi-fetch";
import type { paths as Radarr } from "./generated";

export function createRadarrClient(clientOptions?: ClientOptions) {
  return createClient<Radarr>(clientOptions);
}

But the index.d.ts just says interface paths { after build

[prisis]

You need to export the types in you index.ts file, without a export the tool dont know what should be exported

[benjick]

Wow, sorry about that 🤦 thank you!

[IsaiahByDayah]

So this works, but I'm still a bit confused as to why? I would imagine I should be able to export types from outside of just index.ts, but that doesn't seem to be the case 🤔

// a.ts
export interface INested {
  foo: boolean
}

=====================
// index.ts
export * as a from "./a.ts

I would expect I could then do the following but it doesn't seem to see that I exported INested from within a.ts:

import { type a } from "my-module"

const doThing = (args: a.INested) => { ... }

[IsaiahByDayah]

@prisis Any chance you could help explain why this doesn't work?

[prisis]

Hey :)

tsup works different then tsc (from typescript), tsup need to know witch files you like to exports, because its use the rollup plugin (rollup-plugin-dts) or "@microsoft/api-extractor" (if you choose experimental dts) to generate the types for you, out of the defined files that you provided.

Just as example without the exports https://github.com/visulima/visulima/blob/main/packages/fs/src/index.ts in this file, tsup wouldnt generated the types

[IsaiahByDayah]

Hmmm, ok. Interesting! While a bit strange/less than ideal to me, since I can just re-export types from my index file it’s not a showstopper. I guess I just expected it to behave differently. Might dig into more later and see if there’s something I can config to work how I expected. Either way, thanks for the help!