No .d.ts Declaration Files for JS Files Are Emitted (allowJs: true)

[hediet]

When setting allowJs: true in tsconfig.json, typescript files can import javascript files.
Typescript is also clever about the types used in javascript and infers as much as possible.
Such inferred javascript types might even be exported by typescript files and become part of the library API.

Expected Behaviour

ts-loader should emit declaration files for javascript files when allowJs is set to true and ts-loader is configured to handle javascript files.

Actual Behaviour

ts-loader does not emit declaration files for javascript files that are imported in typescript files. This results in broken declaration files.

Steps to Reproduce the Problem

1. clone https://github.com/hediet/webpack-allowjs-declaration-issue-repro
2. run yarn
3. run yarn build
4. Notice this error (no declaration files for javascript):

Location of a Minimal Repository that Demonstrates the Issue.

https://github.com/hediet/webpack-allowjs-declaration-issue-repro

Btw., thanks for creating and maintaining ts-loader!

[hediet]

I guess this should be fixed by changing this line of code:

if (fileName.match(constants.tsTsxRegex) === null) {

into this, as done in this line:

if (fileName.match(compilerOptions.allowJs === true
      ? constants.dtsTsTsxJsJsxRegex
      : constants.dtsTsTsxRegex;) === null) {

Edit: I can confirm that this fixes this issues. Idk whether it causes other issues.

[appzuka]

I looked at your repo and confirmed what you reported. I can also confirm that when using tsc and allowJs the declaration files are generated, so I don't see any reason why ts-loader should not do this. Perhaps you would like to submit a PR with your proposed fix.

[hediet]

I submitted a PR!

[as-zlynn-philipps]

one... year... later...