Simple snippet to demonstrate behavior of Promise.all

Promise.js

// Timeout
const p1 = new Promise((resolve, reject) => {
	setTimeout(() => {
		resolve("Resolve promise 1");
	}, 3000);
});

const p2 = new Promise((resolve, reject) => {
	setTimeout(() => {
		resolve("Resolve promise 2");
	}, 1000);
});

const p3 = new Promise((resolve, reject) => {
	setTimeout(() => {
		resolve("Resolve promise 3");
	}, 4000);
});

Promise.all([p1,p2,p3])
	.then((res) => {
		console.log(res);
	});


// Requisição

const r1 = fetch('https://jsonplaceholder.typicode.com/posts').then(res => res.json());
const r2 = fetch('https://jsonplaceholder.typicode.com/users').then(res => res.json());
const r3 = fetch('https://jsonplaceholder.typicode.com/comments').then(res => res.json());

Promise.all([r1,r2,r3])
	.then((res) => {
		console.log(res);
	});