On: TypeScript NPM Packages Done Right

[evnix]

I understand the whole CommonJS Vs imports situation.

I have been that vocal minority that keeps complaining about CommonJS support to library authors. But I have given it up for the greater good.

we have a standard now, CommonJS needs to go, why keep pushing non standard stuff in a 2023 article.

[EMM_386 → evnix]

Yes, when working with Angular, you'll see build warnings about CommonJS dependencies.

> ▲ Module 'some-library' used by 'src/app/some.component.ts' is not ESM

> CommonJS or AMD dependencies can cause optimization bailouts.

> For more information see: https://angular.io/guide/build#configuring-commonjs-dependen...

[ushakov → evnix]

The problem is that you can import commonjs modules in ESM but not the other way around. For stepci (https://stepci.com) we have chosen to not support ESM for this very reason. We want that the library “just works” for all our users

[spankalee → ushakov]

You cannot import Common JS from standard JS modules in an environment that doesn't support Common JS, like... all browsers.

Everything should be published as standard modules at this point.

[edwinjm → ushakov]

If you're using TypeScript, you have a build step anyway, so you can easily use ESM.

[ushakov → edwinjm]

Remember we’re using Node. I don’t think TypeScript compiler supports importing ESM into CommonJS files.

Basically we will have to move the library to ESM and then use a bundler like esbuild to compile it to CJS as well for compatibility. It’s a mess

[herpdyderp → ushakov]

Try using the tsx package for running Node in situations like this. It magically “just works”

https://www.npmjs.com/package/tsx

[josteink → ushakov]

> It’s a mess

I think everyone agrees about this.

What people can’t agree about is how to fix it.

[vinnymac → josteink]

I haven’t really struggled too much here.

Maybe an aversion to bundlers exists, but I think tsup and vite are great and simple. We have turbopack on the horizon too.

For small projects I don’t even need a configuration file for tsup to target both formats. For larger more complex projects vite configs tend to be under 50 LoC.

[edwinjm → evnix]

Exactly.