Support for stripping type annotations

[nezarati]

JavaScript engines are moving towards native support for type annotations, as seen in the Type Annotations proposal.

Also, Node.js recently supports TS compilation by embedding the Amaro wasm module. It is limited to inline type annotations and doesn't support features like enums or namespaces. It allows running TypeScript files without prior transformation by stripping type annotations.

Does es-module-shims have plans to support for stripping type annotations?

This feature is useful for users by:

• Reducing build times by eliminating unneeded transformation steps.
• Leveraging native engine support for type annotations as it becomes available.

[guybedford]

While strictly speaking, es-module-shims is designed to be tailored to browser standards, I also really like this idea.

Perhaps the way this can be done is to have a new development build of es-module-shims, that runs type stripping first if the file has a TypeScript extension. This should be relatively straightforward if we just use Amaro (https://www.npmjs.com/package/amaro) like Node.js does.

[guybedford]

I went ahead and implemented a simple POC in #435. Feedback welcome.