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

Make a custom interface extends the Window and add your custom property as optional.

Then, let the customWindow that use the custom interface, but valued with the original window.

It's worked with the typescript@3.1.3.

interface ICustomWindow extends Window {
  MyNamespace?: any
}

const customWindow:ICustomWindow = window;

customWindow.MyNamespace = customWindow.MyNamespace {}