Promise

Promise All

The Promise.all() method takes an iterable of promises as an input, and returns a single Promise that resolves to an array of the results of the input promises. This returned promise will resolve when all of the input's promises have resolved, or if the input iterable contains no promises. It rejects immediately upon any of the input promises rejecting or non-promises throwing an error, and will reject with this first rejection message / error.

const url = ['www.url1.com', 'www.url2.com', 'www.url3.com']

Promise.all(urls.map(url => {
    return fetch(url).then(resp => resp.json())
})).then(results => {
    console.log(result[0])
    console.log(result[1])
    console.log(result[2])
}).catch(() => console.log('error')

With Async Await

const [users, posts, todos] = await Promise.all(urls.map(url => {
    return fetch(url).then(resp => resp.json())
}))
console.log('users', users)
console.log('posts', posts)
console.log('todos', todos)

Promise.AllSettled

Will not return error, but return a result of both reject and resolve after 6 seconds

const promiseOne = new Promise((resolve, reject) => setTimeout(resolve, 6000))
const promiseTwo = new Promise((resolve, reject) => setTimeout(reject, 3000))

Promise.allSettled([promiseOne, promiseTwo]).then(data => console.log(data))