How do you expose class in a module to the global namespace in TypeScript?

Question

The Problem

Given

• I have an existing application containing both modules and global scripts (regular non-module scripts).
  • modules
    • App.ts
  • global scripts
    • alpha.ts contains a class named alpha
    • beta.ts contains a class named beta
    • gamma.ts contains a class named gamma
• I want to convert one class in a global script (gamma.ts) into a module
  • via adding export default before class gamma {} in gamma.ts
• I want to import class gamma into the global namespace (i.e the window object) so it can be accessed by the existing global and module scripts.

What I have tried

I have tried a bunch of things around global.d.ts

e.g.

import gammaAlias from "../scripts/gamma";
export as namespace NS_Global;

declare global {
    var qqq: {n:string};
    namespace ZZZ {
       export var gamma: gammaAlias;
    }
    var gamma: gammaAlias;
}

But none has worked

i.e. TypeScript tells me one of the following

• gamma does not exist
• Cannot use 'new' with an expression whose type lacks a call or construct signature.

github

I have a github repo set up to investigate these questions. https://github.com/penguin020/expose-typescript-modules-globally

ConvertToModulesPOC_original is the working "before" case.

ConvertToModulesPOC is a broken attempt to convert gamma .ts to a module and expose it globally.

PS

The question remains, how do you expose a module to the global namespace?

Any answers using the examples in the github would be particularly appreciated!

Answer 1

I found an answer here in "TypeScript: exposing module types in the global context and why to avoid it";

I have updated the github repo.

The most salient changes I found were:

---

in tsconfig:

"module": "system",

---

in yMod.ts

import gammaAlias from "../scripts/gamma.js";

declare global {
    export type gamma = gammaAlias;
    export const gamma: typeof gammaAlias;
}

(window as any).gamma = gammaAlias;

note: You could have the global ambient declaration in another file, even a *.d.ts file.

---

The link above breaks down the reasons for having three references for each symbol to be exposed globally. It is pretty well explained on that page, so I will only summarize here:

1. Expose the class type to the TypeScript compiler (no code generated)
2. Expose the class object to the TypeScript compiler (so there is an object to call new on; no code generated)
3. Extend the window object to expose the class in the global namespace (generates code).