"use strict";

//------------------------------------------------------------------------------

// Promise Usage

// First class representation of a value that may be made asynchronously and

// be available in the future.

// http://es6-features.org/#PromiseUsage

//------------------------------------------------------------------------------

function msgAfterTimeout (msg, who, timeout) {

return new Promise((resolve, reject) => {

setTimeout(() => resolve(`${msg} Hello ${who}!`), timeout)

})

}

msgAfterTimeout("", "Foo", 100).then((msg) =>

msgAfterTimeout(msg, "Bar", 200)

).then((msg) => {

console.log(`done after 300ms:${msg}`)

})

//------------------------------------------------------------------------------

// Promise Combination

// Combine one or more promises into new promises without having to take care

// of ordering of the underlying asynchronous operations yourself.

// http://es6-features.org/#PromiseCombination

//------------------------------------------------------------------------------

function fetchAsync (url, timeout, onData, onError) {

// …

}

let fetchPromised = (url, timeout) => {

return new Promise((resolve, reject) => {

fetchAsync(url, timeout, resolve, reject)

})

}

Promise.all([

fetchPromised("http://backend/foo.txt", 500),

fetchPromised("http://backend/bar.txt", 500),

fetchPromised("http://backend/baz.txt", 500)

]).then((data) => {

let [ foo, bar, baz ] = data

console.log(`success: foo=${foo} bar=${bar} baz=${baz}`)

}, (err) => {

console.log(`error: ${err}`)

})