Extending TypeScript Global Object in NodeJS

12.05.2021 — nodejs, typescript, global — 1 min read

You want to add a function to global object in NodeJS environment

type MyFunctionType = () => void;

global.myFunctionName = () => {
  console.log("hi");
};

To extends global object in TypeScript, you need to augment the global namespaces

declare global {
  namespace NodeJS {
    interface Global {
      myFunctionName: MyFunctionType
    }
  }
}

With this in place, you now can call the function like this

global.myFunctionName();

To call the function without global., you need to augment the globalThis type

declare global {
  namespace NodeJS {
    interface Global {
      myFunctionName: MyFunctionType
    }
  }

  namespace globalThis {
    const myFunctionName: MyFunctionType
  }
}

With this in place, you now can call the function like this

myFunctionName();

That's it. Thanks for reading.