RE: https://www.jimhribar.com/adventures-in-async-await/

serial-vs-parallel.js

// In response to the following article:
//      https://www.jimhribar.com/adventures-in-async-await/
// 
// Using Javascripts Object.map function, it's possible to get an array of promises
// which can then be awaited simultaneously, which will execute all of them in parallel.
//
// This is faster than the looping approach in the article, which awaits each Promise individually.
//
// Console output:
//      parallelJob: 501.226ms
//      parallelJob: 2,2,2,2,2,2
//      serialJob: 5011.910ms
//      serialJob: 2,2,2,2,2,2

const double = function (value) {
    return new Promise(resolve => {
        setTimeout(function () {
            resolve(value * 2);
        }, 500);
    });
};

const values = [1, 2, 1, 2, 1, 2, 1, 2, 2, 2];

const runSerialJob = (async () => {
    const results = [];

    const job = async () => {
        for (let value of values) {
            if ((await double(value)) == 4) {
                results.push(value);
            }
        }
    };

    const timerLabel = "serialJob";
    console.time(timerLabel);
    job().then(() => {
        console.timeEnd(timerLabel);
        console.log(`${timerLabel}: ${results}`);
    });
});

const runParallelJob = (async () => {
    const job = async () => {
        const doubledValueAndValuePromises = values.map(async (value) => {
            const doubledValue = await double(value);
            return {
                value,
                doubledValue
            };
        });

        const listOfDoubledValueAndValue = await Promise.all(doubledValueAndValuePromises);

        const results = listOfDoubledValueAndValue
            .filter(doubledValueAndValue => doubledValueAndValue.doubledValue === 4)
            .map(doubledValueAndValue => doubledValueAndValue.value);

        return results;
    };

    const timerLabel = "parallelJob";
    console.time(timerLabel);

    const results = await job();

    console.timeEnd(timerLabel);
    console.log(`${timerLabel}: ${results}`);
});

runSerialJob();
runParallelJob();