npm 包中的自定义 TypeScript 声明文件不起作用

Question

I have created a simple package that contains an index.d.ts at the root. Here is the content:

declare var foo: number;

I have then created a separate project which adds that package using npm link. In Visual Studio Code, foo is not getting picked up. I have also tried adding "types": "./index.d.ts" to the package.json where index.d.ts resides. It is not working. In my playground project, I have the following tsconfig.json:

{
  "compilerOptions": {
    "target": "es2018",
    "module": "esnext",
    "jsx": "preserve",
    "strict": false,
    "moduleResolution": "node",
    "esModuleInterop": true,
    "resolveJsonModule": true
  }
}

Why is the index.d.ts not getting picked up by Visual Studio Code in the project?

Answer 1

I don't know, how your library package will be included, so first some common rules:

If you import the package as module, index.d.ts at package root (or with package.json entry) will be picked up automatically via module resolution .

If package types are just global type declarations (nothing to import from a module), TS would find it automatically in node_modules/@types of any enclosing folder, see typeRoots configuration.

So, let's say you just have declare var foo: number; in the file (it is then a global declaration file) and types are under node_modules/my-lib , not node_modules/@types/my-lib , then you would need to manually tell TS to include it in the compilation.

Easiest way is probably to add it to the files property of tsconfig.json , which specifies additional files to be included explicitely. See the good example section in the docs . An alternative would be to adjust typeRoots , but that is probably overkill here.

My guess is there is a second error cause: npm link will create a symlink and per default TS uses those paths, the symlinks resolve to (the real paths).

We can fix that by enabling --preserveSymlinks option ( tsc --preserveSymlinks ) to use location of the symbolic link file instead (see also compiler options ). What docs say to this option:

In this mode, references to modules and packages (eg imports and /// directives) are all resolved relative to the location of the symbolic link file, rather than relative to the path that the symbolic link resolves to.