async-examples.js

function createCallback(returnValue) {
    return (callback) => {
        setTimeout(() => {
            callback(null, returnValue);
        });
    };
}

function createPromise(returnValue) {
    return new Promise((resolve) => {
        setTimeout(() => {
            resolve(returnValue);
        }, 300);
    });
}

// Example one
async.race([
    createCallback('job1'),
    createCallback('job1'),
    createCallback('job1')
], (err, result) => {
    console.log('Race callback', err, result);
});

Promise.race([
    createPromise('job1'),
    createPromise('job2'),
    createPromise('job3')
]).then((result) => {
    console.log('Promise race', result);
}).catch((err) => {
    console.log(err);
});

// Example two
async.parallel({
    job1: createCallback('job1'),
    job2: createCallback('job2'),
    job3: createCallback('job3')
}, (err, result) => {
    console.log('Parallell callback', err, result);
});

Promise.all([
    createPromise('job1'),
    createPromise('job2'),
    createPromise('job2')
]).then((results) => {
    console.log('Parallell promise', results);
}).catch((err) => {
    console.log(err);
});

// Example three
async.seq(
    createCallback('job1'),
    (result, callback) => {
        createCallback(result + '-job2')(callback);
    },
    (result, callback) => {
        createCallback(result + '-job3')(callback);
    }
)((err, result) => {
    console.log('Callback sequence', err, result);
});

createPromise('job1')
    .then((result) => {
        return createPromise(result + '-job2');
    }).then((result) => {
        return createPromise(result + '-job3');
    }).then((result) => {
        console.log('Promise sequence', result);
    }).catch((err) => {
        console.log(err);
    });