Should emitFile take an importer?

[jakearchibald]

Feature Use Case

Take plugin code like this:

const prefix = 'typescript:';
{
  async resolveId(id, importer) {
    if (!id.startsWith(prefix)) return null;

    const realId = id.slice(prefix.length);
    const resolveResult = await this.resolve(realId, importer);
    if (!resolveResult) {
      throw Error(`Cannot resolve ${realId}`);
    }
    return prefix + resolveResult.id;
  },
}

Which converts typescript:./whatever.ts to typescript:/full/path/to/whatever.ts, based on the importer.

However, another plugin cannot invoke this via emitFile:

this.emitFile({
  type: 'chunk',
  id: 'typescript:./whatever.ts',
});

The other plugin would have to understand the typescript: prefix, and handle resolving itself.

Feature Proposal

this.emitFile({
  type: 'chunk',
  id: 'typescript:./whatever.ts',
  importer: '…',
});

The value of importer would be passed to resolveId.

[lukastaegert]

However, another plugin cannot invoke this via emitFile

I do not believe this is true. An id from emitFile should run through the whole chain of resolveId, load and transform. Not happy to implement a new mechanism on top of the existing one.

[jakearchibald]

An id from emitFile should run through the whole chain of resolveId

Right, but what will importer be?

[lukastaegert]

Ah, sorry, I totally misunderstood what you meant. You mean the second argument of resolveId. I thought you meant something like a loader.

[lukastaegert]

Yes, being able to configure the importer would make sense when emitting a file.

[jakearchibald]

Yep! Sorry for explaining it badly.

[lukastaegert]

Please have a look if #3442 would work for you.