nestedAsync.js

async function fetchAvatarUrl(userId) {
	const response = await fetch(`https://catappapi.herokuapp.com/users/${userId}`)
	const user = await response.json();
	
	return Promise.all(user.cats.map(async (catId) => {
		const response = await fetch(`https://catappapi.herokuapp.com/cats/${catId}`)
		const catData = await response.json()
		return catData.imageUrl
	}))
}

const result = fetchAvatarUrl(123)

console.log(result);

simpleAsyncAwait.js

function fetchAvatarUrlWithPromise(userId) {
	return fetch(`https://catappapi.herokuapp.com/users/${userId}`)
			.then(response => response.json())
			.then(data=>data.imageUrl)
}

async function fetchAvatarUrlWithAsync(userId) {
	const response = await fetch(`https://catappapi.herokuapp.com/users/${userId}`)
	const data = await response.json();
	return data.imageUrl
}

const result = fetchAvatarUrlWithPromise(123)

console.log(result);

const asyncResult = fetchAvatarUrlWithAsync(123)

console.log(asyncResult);