Where should I place custom .d.ts files?

I'm trying to provide typings for the package that does not have them:

error TS7016: Could not find a declaration file for module 'inputmask-core'. './node_modules/inputmask-core/lib/index.js' implicitly has an 'any' type.
Try `npm install @types/inputmask-core` if it exists or add a new declaration (.d.ts) file containing `declare module 'inputmask-core';`

I'm using ts-loader in webpack with typescript 2.4.2, and I have the following type roots set up in tsconfig.json:

"typeRoots": [
  "./node_modules/@types",
  "./src/client/types"
]

I tried to mimic the package structure in node_modules/@types:

src/client/types
|--inputmask-core
  |--index.d.ts

With the following in index.d.ts:

declare class InputMask {}
export default InputMask;

But the error is still there. What am I doing wrong? Where should I place those custom .d.ts files?

And what is the difference between node_modules/@types and any other type root? Why does TypeScript treat them differently?

Use paths instead of typeRoots

• https://github.com/Microsoft/TypeScript/issues/22217#issuecomment-369783776
• https://www.typescriptlang.org/docs/handbook/module-resolution.html#path-mapping

> "typeRoots" is meant for global code. i.e. something that is > declared in the global namespace, and you want to include it. For > modules, they have their own scope, all you need is path mapping.. > something like:

{
    "compilerOptions": {
        "target": "es2017",
        "baseUrl": "./",
        "paths": {
            "*": [ "src/client/@custom_types/*"]
        }
    },
    "exclude": [ "node_modules", "src/client/@custom_types", ... ]
}

Note: baseUrl is required with paths, and you probably also want to add the dir to exclude.

Possible solution: place the following in index.d.ts, and it will compile:

declare module "inputmask-core" {
    declare class InputMask {}
    export default InputMask;
}

I still don't understand the special handling that node_modules/@types gets, though.

There is a lot of packages that are not typescript packages, so to fix this error just change compilerOptions.strict to false in tsconfig