Using the window global is deprecated and scheduled for removal in Deno 2.0. Deno does not have a window and typeof window === "undefined" is often used to tell if the code is running in the browser.

Invalid:

const a = await window.fetch("https://deno.land");

const b = window.Deno.metrics();
console.log(window);

window.addEventListener("load", () => {
  console.log("Loaded.");
});

Valid:

const a1 = await fetch("https://deno.land");
const a2 = await globalThis.fetch("https://deno.land");
const a3 = await self.fetch("https://deno.land");

const b1 = Deno.metrics();
const b2 = globalThis.Deno.metrics();
const b3 = self.Deno.metrics();
console.log(globalThis);

addEventListener("load", () => {
  console.log("Loaded.");
});