test.promises.ts

"use strict";
// https://stackoverflow.com/questions/45285129/any-difference-between-await-promise-all-and-multiple-await
// also https://jsfiddle.net/znup6vLj/

//console.clear();

function delay(ms: number) {
    return new Promise(resolve => {
        setTimeout(resolve, ms);
    });
}

interface Empty {}
interface Person { name: string, age: number }

// IIFE https://developer.mozilla.org/en-US/docs/Glossary/IIFE
(async () => {

    const time1 = new Date().getTime();
    const arr: Promise<number>[] = [
        delay(60).then(() => 5),
        delay(60).then(() => 10),
        delay(100).then(() => 15),
        Promise.resolve(20),
    ]
    const funcs: (Promise<number>|number|void)[] = [
        async () => {
            console.log(60);
            return await Promise.resolve(60);
        },
        () => { console.log(65); return 65; },
        () => { console.log(70); return Promise.resolve(70); },
        // https://stackoverflow.com/questions/38708550/difference-between-return-await-promise-and-return-promise
        // would not be caught if there was an error here
        // use https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/allSettled to contain errors
        //() => { console.log(75); return Promise.reject(75); },
        () => { console.log(80); Promise.resolve(80); },
        // https://stackoverflow.com/a/24250926/198348
        () => { return Promise.resolve(<Empty>{}); },
        () => { return Promise.resolve(<Person>{name: "E", age: 1}); },
    ].map(f => f());

    const data = await Promise.all([...arr, ...funcs]);
    const time2 = new Date().getTime();

    console.log("done", time2 - time1);
    console.log(data);

})();