How to use a local typescript declaration file for an installed module?

Question

When I installed a non popular module that doesn't have a published type declaration under @types namespace, I'm stuck. I know how to write a declaration file, but I don't know how to make typescript compiler aware of it. The typescript documentation doesn't mention how to do it. The docs only mention to search for type declaration and if not found, publish a new one but doesn't mention how to do it without publishing.

So, say I installed a package named xyz and I know the public api that it exposes. Then, I write a type declaration file that matches the exposed api. Then, How to make typescript compiler aware of it?

Oscar Paz · Accepted Answer · 2018-04-25 11:01:49Z

4

Just add a <module-name>.d.ts file to your project, and TypeScript should become aware of it automatically. You don't need to import it or anything, just to be in the folders processed by TypeScript

answered Apr 25, 2018 at 11:01

Oscar Paz

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5 Comments

Mas Bagol Over a year ago

Could you be more specific, where should I put that file? Say, all my typescript codes is under src/ directory, where should I put that file?

Paleo Over a year ago

Notice: In the definition file, the author must wrap the exported members in: declare module "xyz" { ... }.

Oscar Paz Over a year ago

@MasBagol, put it under src/, yes. You can also add a folder types under you src if you want, it doesn't matter. And no, you don't need to 'export' anything, as it is an ambient declaration file.

Mas Bagol Over a year ago

Ah, okay. Thanks :)

Justin Bailey Over a year ago

Very important that the file begin with ``` declare module '<module name>'; ```

transporter_room_3 · Accepted Answer · 2018-04-25 11:12:30Z

0

Does your project include a tsconfig.json file? If so you can specifiy paths to type definitions under the compilerOptions:

{
   "compilerOptions": {
       "typeRoots" : ["./typings"]
   }
}

About 'tsconfig.json' in the TypeScript handbook

answered Apr 25, 2018 at 11:12

transporter_room_3

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