Importing typescript-only packages.

[heavy haven]

I would like to import typescript-only npm package.
When building i receive "Cannot use import statement outside a module" error.
How can I make sure that this typescript file gets transpiled or do i have to include build step in this package that emits .js and .d.ts files?

[mint rain]

there is no such thing as typescript-only packages

the errors you are facing is related to ES modules

you can only use an import statement in a file that is an ES module

a file is only an ES module if it has at least one export statement

👉 to solve the problem, just add an export statement to your file, to turn it into an ES module

if you have nothing to export, you can export an empty object like so

export {};

👉 you could also set the option moduleDetection to force to force all files to be considered as ES modules

https://www.typescriptlang.org/tsconfig#moduleDetection

@heavy haven

[lime current]

Just to nitpick, technically there are types only packages

[heavy haven]

I mean that I want to have private npm package that will only contain ts file, that will be imported just like regular files in typescript project.

The problem is that when this code is in node_modules, it is not treated like regular .ts file

And it seems to be related to the bundling process

So I would like to know if this is somehow doable with tsc alone or other tools

Normally tsc, will generate file with require/import statements so when the output will run it will have problem because node cannot run ts files

So, the general question is can node_module not include build step to js, so that the file gets imported in project just like it was an ordinary file in project.

[heavy haven]

My package already had exported function

Also I want to say that I would not like to set whole project's where package is imported package.json to include type: "module"

[lime current]

Yeah don't do that

build it to .js with declaration: true and declarationMap: true

[lime current]

I've never seen it done. I guess that TS looks only for .d.ts files in node_modules, but not sure

I think you would have to do a folder with symlinks into the project folder if you wanted that

@heavy haven

[heavy haven]

I can import ts files and types are correctly discovered, but it its not treated by build tool as something to be transpiled

[lime current]

Oh really?

So your issue is that tsc doesn't compile the .ts files in node_modules? I wouldn't expect it to

Have you specified the folder as included in tsconfig "include" section?

Hmm that would gives problems because you'd get a node_modules folder in dist, or it would complain that its not in dist