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 those who want to set a computed or dynamic property on the window object, you'll find that not possible with the declare global method. To clarify for this use case

window[DynamicObject.key] // Element implicitly has an 'any' type because type Window has no index signature

You might attempt to do something like this

declare global {
  interface Window {
    [DyanmicObject.key]: string; // error RIP
  }
}

The above will error though. This is because in Typescript, interfaces do not play well with computed properties and will throw an error like

A computed property name in an interface must directly refer to a built-in symbol

To get around this, you can go with the suggest of casting window to so you can do

(window as any)[DynamicObject.key]