Extending TypeScript Global object in node.js

As of node@16 the NodeJS.Global interface has been removed in favor of globalThis.

You can declare new global variable in a module file as:

declare global {
  var NEW_GLOBAL: string;
}

And in a non-module file (no top-level import/export) as:

declare var NEW_GLOBAL: string;

Important note: variable must be declared as var. let or const variables doesn't show up on globalThis.

I saw this SO post and tried this:

You probably have something like vendor.d.ts:

// some import 
// AND/OR some export

declare module NodeJS  {
    interface Global {
        spotConfig: any
    }
}

Your file needs to be clean of any root level import or exports. That would turn the file into a module and disconnect it from the global type declaration namespace.

More : https://basarat.gitbooks.io/typescript/content/docs/project/modules.html