global variable in typescript isnt working

I have a problem with the implementation of the signin function in my application. I have a global declaration for this function, but while using it I got an error saying 'Element implicitly has an 'any' type because type 'typeof globalThis' has no index signature.' I have tried several solutions but no luck. Can you help me solve this problem?

import request from 'supertest';
import { app } from '../app';

// Deklarata globale për funksionin `signin`
declare global {
  namespace NodeJS {
    interface Global {
      signin: () => Promise<string[]>;
    }
  }
}


global.signin = async () => {
  const email = 'test@test.com';
  const password = 'password';

  const response = await request(app)
    .post('/api/users/signup')
    .send({
      email,
      password
    })
    .expect(201);

  const cookie = response.get('Set-Cookie');

  return cookie;
};


it('responds with details about the current user', async () => {
  const cookie = await global.signin();

  const response = await request(app)
    .get('/api/users/currentuser')
    .set('Cookie', cookie)
    .send()
    .expect(200);

  expect(response.body.currentUser.email).toEqual('test@test.com');
});

so it seems the issue we're running into stems from TypeScript's strict type-checking. TypeScript is complaining because it doesn't recognize the type of globalThis as having an index signature, which it needs to understand that we're adding a property (signin) to it.

To tackle this, we need to provide TypeScript with a clearer picture. We can do this by explicitly telling it that the global object can have any property. By casting global as any, we're essentially saying, "Hey TypeScript, don't worry too much about strict typing here, we're confident that global can handle whatever we throw at it."

So, here's what I think should work:

// Adjust the global declaration
declare global {
  namespace NodeJS {
    interface Global {
      signin: () => Promise<string[]>; // Your signin function signature
    }
  }
}

// Change `global` to `any`
(global as any).signin = async () => {
  // Your signin function implementation remains the same
};

This should do the trick! By explicitly casting global as any, we're telling TypeScript to chill out a bit and trust us on this one. This approach should resolve the error and allow our signin function to work smoothly as intended.