Add --preserveModules (similar to babel --out-dir)

[yordis]

Current Behavior

We need to specify an entry point.

Desired Behavior

Specify --outDir over an entry point

Suggested Solution

I am interested in having TypeScript/Babel CLI like compilations rather than outputting a single file.

Who does this impact? Who is this for?

All users, friendly for ESM builds without having to import everything in the entry file.

Describe alternatives you've considered

• TypeScript compiler but I don't have support for the Babel plugins 🤷‍♂
• Babel CLI but I don't have support for SASS loaders 🤷‍♂

Additional context

[swyxio]

popular feature request. i'll leave it to jared.

[agilgur5]

@yordis it sounds like what you're looking for is Rollup's preserveModules option. If that's correct, you could do that by modifying tsdx.config.js to add config.preserveModules = true:

module.exports = {
  rollup(config, opts) {
    if (opts.format === 'esm') {
        config = { ...config, preserveModules: true }
        config.output = { ...config.output, dir: 'dist/', entryFileNames: '[name].esm.js' }
        delete config.output.file
    }
    return config
}

One last edit: updated to the same as #276 (comment), please see #276 for discussion and evolution of the preserveModules use-case and workaround.

You'll have to change your package.json module to index.esm.js for this (unavoidable with output.dir).

This is only for ESM as, per #276 (comment), CJS preserveModules doesn't quite work the same way and has various consequences. For multi-entry support, please see #367

---

EDIT: I tried this myself, and had to add config.output.dir = ... above as well as delete config.output.file, because output.dir is required when using preserveModules and because output.file is mutually exclusive with output.dir.

The problem with this is that it only outputs minified CJS files, because output.file can't be specified, and therefore the various file extensions like .esm.js and .cjs.js etc end up overwriting each other.
That might be fine for your use case, but isn't ideal. The only other simple workaround would be to have a separate output.dir for each build format (e.g. /dist/cjs/, /dist/esm/, etc), but that's non-trivial and potentially impossible to do with just a tsdx.config.js (might require internal changes to support). EDIT: can use config.output.dir = process.cwd() + '/dist/' + config.output.format + '/' for this like in #382 , but I believe it will still be missing non-minified/dev CJS output.

[agilgur5]

Going to close this as a duplicate of #276 since these are around the same feature and the use-case has evolved there.

Please see #276 for discussion on preserveModules, #535 for a WIP flag for that, and #367 for multi-entry support.

I've updated my comment above to the latest workaround from #276 as well.