Allow --declaration with --allowJs

[blakeembrey]

From #7535, it would be useful for JavaScript package authors to have the ability to generate declarations from their project. This would help with getting started on a type definition (it would be populated with known interfaces/functions/types that are exported) and would also allow the creation of continuous integration scripts that check the JavaScript types with the hand-coded definition for inconsistencies.

[mhegazy]

PRs are welcomed. the fix should be removing the error, making sure the call is wired correctly, adding tests and making sure the declaration emitter handles the JS types correctly,

[bengreenier]

anyone currently working on this? If not i may take a stab at it.

[mhegazy]

anyone currently working on this? If not i may take a stab at it.

got for it.

[endel]

This would be definitely helpful 👍

[trusktr]

👍

[bowdenk7]

Take a look at dts-gen and let us know what you think. At the moment it doesn't do a good job of detecting changes between generations. But let us know if this helps!

[blakeembrey]

Thanks @bowdenk7!

Would a simple approach like #7535 (comment) (internally) be enough to check if the definition has changed? It would be great to be able to run dts-gen in CI and error when there has been un-documented API changes to prompt an update to the .d.ts.

[MicahZoltu]

Another use-case for this is that I have some plain JS tests that I use as both a form of documentation and as a way of validating that my code is callable from native ES5 in a way that is reasonable. All of my distributed source code is sourced from TypeScript and I would like to generate definition files for NPM publishing. However, because I have that one JS test sitting in my source tree I need allowJs=true so the test will correctly land in the output directory (not committed to source control) and be run along with all of my other tests. This, of course, means I can't have TSC output definition files for the rest of my project.

[nojvek]

@bengreenier Wondering if you have made much progress on this? Let me know if there is anyway I can help speed things up. Would love to see this out in the wild.

[mhegazy]

Based on the discussion in #15747, we would like to take this change.

[bengreenier]

@nojvek i've also made no more progress 😁 - got pulled into a different project and had to re-prioritize.

[industrialCoder]

@studds when I say a large legacy library, I mean a very large legacy library... The time it would take to convert all of the .js files over to .ts and add the syntax required to make them valid TS (even typing everything as any) would be obscene to say the least. Is saying type = importSourceType == js ? any : determineTSType(source) really that huge of a lift? Not familiar with the TS compiler code, but seems like this would be good bandaid solution that would help a lot of people out and should be much easier to implement than the solutions a lot of other people here are purposing....

[amitbeck]

That's my exact use case - generating Protobuf source code which includes both .js and .d.ts files.

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On Wed, Sep 4, 2019 at 10:53 PM Christian Stewart ***@***.***> wrote: I generate some Protobuf files (.js and .d.ts) which I want to include with my library. I'd expect the Typescript compiler to pull the files together into a bundle and produce combined definitions, but I get the "simultaneous allowJs and declarations not allowed" issue — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#7546?email_source=notifications&email_token=AFLJ6KTEVJR5RBKLSL3RC7DQIAG4HA5CNFSM4B6JHBJ2YY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOD54YOPI#issuecomment-528058173>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AFLJ6KUME3FNKB6EKOADFMLQIAG4HANCNFSM4B6JHBJQ> .

[paralin]

@amitbeck I solved it for now by generating types separately and using --allowJs=false on the type generation step.

[rbiggs]

I have an issue opened on TypeScript problems with understanding imported JSDoc types from imported node modules. It's currently flagged as backlog. Feel free to comment there to push this along: #33136. Getting this fixed would allow JavaScript authors to provide JSDoc types for their code that end users could take advantage of for type linting and Intellisense in VSCode with allowjs set to true.

[OliverJAsh]

At Unsplash, this is blocking us from using project references aka composite (because composite requires declaration to be turned on).

[nomcopter]

Glorious day! Thanks @weswigham! Looks like this is slated for 3.7? Man that is going to be a great release.

[yin]

Does the conversion mechanism recognize node packaging? It seems it generates one module per file, although Node.js exports one module per dependency.

[ljharb]

A module is a file is a module; an npm package has 0, 1, or N files/modules.

[yin]

You are right. Still, it does not help with producing declarations compatible with the node module lookup mechanism. You may want to refer to this question on StackOverflow for an example of what is precisely happening: https://stackoverflow.com/questions/59564524/generating-typescript-declarations-for-re-exported-js-functions-in-a-node-js-mod

[cecetipoi]

is this resolved?