TypeScript: How to define custom typings for installed npm package?

Create a new file, called it rx-node.d.ts and make sure it's referenced in your tsconfig.json either directly or from another file, for example typings/index.d.ts. Then you can start with something like this:

///<reference path="rx.d.ts" />

declare namespace RxNode  {

    export interface Emitter<T>{

    }

    export function toEventEmitter<T>(observable: Rx.Observable<T>, eventName: string): Emitter<T>;
}

This question/answer might be helpuful: How to write d.ts file from existing .js file?

If you create a nice, high quality typings definition file, contribute to https://github.com/DefinitelyTyped/DefinitelyTyped

Beware, this is old question (2016) regarding managing definitions using typings which is deprecated in favor of installing them straight via npm

---

You can add custom definitions to typings.json. For example having following folder structure:

/typings
    /custom
        rx-node.d.ts
    /global
        ...

where rx-node.d.ts is your custom typings file. For example:

declare module RxNode {
    export interface ...
}

Then install with a command

typings install file:typings/custom/rx-node.d.ts --save --global

---

Or manually: in typings.json add reference to this typings file:

{
    "name": "TestName",
    "version": false,
    "globalDependencies": {
        "rx-node": "file:typings/custom/rx-node.d.ts"
    }
}

And run typings install