AsyncFunction is not defined, yet MDN documents it's usage

Question

There is an article AsyncFunction - JavaScript on MDN. It shows the following snippet:

new AsyncFunction([arg1[, arg2[, ...argN]],] functionBody)

Yet in both Mozzila Firefox 55 and Google Chrome, this constructor is not defined at all:

I found out that (async function() {}).constructor really is AsyncFunction, but why can't I see it in global scope?

Answer 1

As mentioned in the Mozilla docs "Note that AsyncFunction is not a global object."

Therefore you can't access it as a property of the window object like other global constructors. It must be obtained by interrogating an instance of an async function:

From the docs:

const AsyncFunction = Object.getPrototypeOf(async function(){}).constructor;