Node.js Global Variable And Typescript

I need to have some strongly-typed global variables. As mentioned here: Extending TypeScript Global object in node.js, in order to add fields to the global variable I need to add a

Solution 1:

Here's an approach. I don't know if this is the 'correct' way of doing things, but it works for me with TypeScript 3.7.4.

1. Assuming your source files live in a folder src, create a new folder src/types and create a file global.d.ts in this folder.
2. Author your declarations using one of the following strategies:
   • If you need to import external types into your declaration file, use the following syntax:

import { Express } from'express';

declareglobal {
  namespaceNodeJS {
    interfaceGlobal {
      __EXPRESS_APP__: Express;
    }
  }
}

• If your declaration file does not contain any imports, the above will not work, and you'll need to use this syntax instead:

declarenamespaceNodeJS {
  interfaceGlobal {
    __CONNECTION_COUNT__: number;
  }
}

4. Make sure your global.d.ts file (and any other files you might add to src/types) is picked up by the TypeScript compiler, by adding the following to your tsconfig.json file:

{"paths":{"*":["node_modules/*","src/types/*"]}}

5. Use the global variable as normal inside your code.

// Below, `app` will have the correct typingsconst app = global.__EXPRESS_APP__;

Solution 2:

I found this works.

Have one file that declares the property on the NodeJS.Global interface with the any type. This file has to be clean of imports or refrences.

node.d.ts

declarenamespaceNodeJS{
    interfaceGlobal {
        foo: any
    }
}

Then in the second file you declare a global variable that has the correct type.

global.d.ts

import IFoo from'../foo'declareglobal {

  constfoo:Ifoo

}