type 'typeof globalThis' has no index signature

Question

i get this error whenever i try to add a function to the global nodejs global namsepace in a TypeScript environment.

Element implicitly has an 'any' type because type 'typeof globalThis' has no index signature

declaring the global namespace

declare global {
  namespace NodeJS {
    interface Global {
      signin(): string[]
    }
  }
}

so if i try this

global.signin = () => {}

it returns a

Element implicitly has an 'any' type because type 'typeof globalThis' has no index signature

Answer 1

I was having a similar issue and I found that node's global typings were changed recently-ish; you can now override them by doing:

// global.d.ts
declare global {
    function someFunction(): string;
    var someVariable: string;
}

Note: this will not work with let or const you must use var.

// index.ts
global.someFunction = () => "some value";
global.someVariable = "some value";

Answer 2

You have to use the var keyword in declare global, and remove namespace NodeJS {.
Like this:

//globals.d.ts
import type { EventEmitter } from "events";
declare global {
    var myGlobal: EventEmitter;
}

/// <reference path="globals.d.ts" />
//index.ts
// reference needs to be at top of file
import { EventEmitter } from "events";
global.myGlobal = new EventEmitter();
global.myGlobal // EventEmitter type: EventEmitter
window.myGlobal // EventEmitter type: EventEmitter

Or if you don't have any imports in the .d.ts file:

//namedoesntmatter.d.ts
declare var a: string;

//index.ts
global.a = "Hello"
global.a //Hello type: string
window.a //Hello type: string