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

Below is an example for Node v16

// globals.d.ts
declare module globalThis {
    var signin: () => string[];
}

Answer 3

I had the same problem with a svelte.kit app. my database module use a global variable to store the dbClient as a promise. VSCode stop complain when the global.d.ts file had this content.

import type { MongoClient } from 'mongodb'

declare global {
  namespace globalThis {
    var _mongoClientPromise: Promise<MongoClient>
  }
}

Answer 4

You should declare a global declared as interface in global.d.ts like this:

export interface global {}
declare global {
  var signin: ()=>string[]
}

The vscode gives correct code hints

Answer 5

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

Answer 6

I too had the same issue. Fixed it by the below code.

declare global {
        function signin(): Promise<string[]>
}

Answer 7

This is how I solved with Node.js V16+

// global.d.ts

export declare global {
   declare module globalThis {
      var MyVar: object;
   }
}

Answer 8

I tried everything I found here, but nothing worked.
Even stranger, VSCode showed NO TypeScript errors, but running tsc still threw:
TS7017: Element implicitly has an 'any' type because type 'typeof globalThis' has no index signature.

After hours, I realised I forgot an "include": [ "src/app.ts" ] line in my tsconfig.json file.

Note to future self and for those who may have made the same mistake:
If you have explicitly provided one or more files in TypeScript's config with include, and that does not include the *.d.ts file, where you declared your globals, the build will fail with this error, even if VSCode shows no error (because it sees the global declaration, but TypeScript won't).

Answer 9

in my own case i didn't quite realize until later that the global namespace i declared was case sensitive.

instead of this. before my question was edited it was namespace NODEJS

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

it was supposed to be this

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

pay attention to NODEJS and NodeJS. After i made these changes, typescript was cool with it and it work the way i expected it to.

Answer 10

just declare variable by var keyword. like this:

// eslint-disable-next-line no-var
var hello = () => { console.log("hello world"); };
// eslint-disable-next-line no-var
var hi: () => number;

globalThis.hello();
globalThis.hi = () => 143;

You can declare variables in .d.ts files, too.

Answer 11

This is work for me during connect db with next 13.4

declare global {
  var mongoose: { conn: any; promise: any };
}

Answer 12

Create the global.d.ts file and copy the following code:

declare global {
  declare module globalThis {
    var uniqueId: string;
  }
}

export {};

And finally, add "include": ["global.d.ts"] to the tsconfig.json file

Done!