It's possible to create an async function in Node.js that runs in parallel?

Question

My goal is to run the longRunnigTask and the quickTask functions in parallel:

function longRunnigTask() {
    return new Promise((resolve) => {
        console.log('longRunnigTask started');
        for (let i = 0; i < 999999999; i++) {};
        console.log('longRunnigTask ended');
        resolve();
    });
}
function quickTask() {
    return new Promise((resolve) => {
        console.log('quickTask started');
        console.log('quickTask ended');
        resolve();
    });
}


(function() {
    Promise.all([
        longRunnigTask(),
        quickTask()
        ]);
})();

My expected output is:

longRunnigTask started
quickTask started
quickTask ended
longRunnigTask ended

But I get:

longRunnigTask started
longRunnigTask ended
quickTask started
quickTask ended

It's possible to achieve this without external libraries or I'm doing something wrong?

Answer 1

In your main long block loop you can do some super tiny pauses like this

 const timeout = (ms) => new Promise(resolve => setTimeout(resolve, ms)); function longRunnigTask() { return new Promise(async (resolve) => { console.log('longRunnigTask started'); for (let i = 0; i < 999999999; i++) { if(i === 5555) await timeout(1); }; console.log('longRunnigTask ended'); resolve('res from long'); }); } function quickTask() { return new Promise((resolve) => { console.log('quickTask started'); console.log('quickTask ended'); resolve('res from quick'); }); } (async () => { longRunnigTask().then((res) => console.log(res)); quickTask().then((res) => console.log(res)); })();