How do you explicitly set a new property on `window` in TypeScript?

Question

I setup global namespaces for my objects by explicitly setting a property on window.

window.MyNamespace = window.MyNamespace || {};

Answer 1

For reference (this is the correct answer):

Inside a .d.ts definition file

type MyGlobalFunctionType = (name: string) => void

If you work in the browser, you add members to the browser's window context by reopening Window's interface:

interface Window {
  myGlobalFunction: MyGlobalFunctionType
}

Same idea for NodeJS:

declare module NodeJS {
  interface Global {
    myGlobalFunction: MyGlobalFunctionType
  }
}

Now you declare the root variable (that will actually live on window or global)

declare const myGlobalFunction: MyGlobalFunctionType;

Then in a regular .ts file, but imported as side-effect, you actually implement it:

global/* or window */.myGlobalFunction = function (name: string) {
  console.log("Hey !", name);
};

And finally use it elsewhere in the codebase, with either:

global/* or window */.myGlobalFunction("Kevin");

myGlobalFunction("Kevin");