How to extend the 'Window' typescript interface

Question

In my example, I\'m trying to extend the TS Window interface to include a polyfill for fetch. Why doesn\'t matter. The question is \"how do I tell T

Answer 1

You need the declare global

declare global {
  interface Window {
    fetch:(url: string, options?: {}) => Promise
  }
}

This works then:

window.fetch('/blah').then(...);