orchestrator for composing tasks

example.js

const { series, parallel } = require('./orchestrator.js');


const buildSync = () => 'this was build synchronously';
const buildAsync = () => Promise.resolve('this could have been made asyncronously');


const tasks = series(
  series(buildAsync, buildAsync),
  series(buildAsync, buildSync),
  parallel(buildAsync, buildSync, buildAsync),
);

tasks()
  .then(results => console.log(results))
  .catch(err => console.error(err));

orchestrator.js

const chalk = require('chalk');


function log(name, message) {
    console.log([
        chalk.bold(`[${chalk.green(name)}]`),
        '-',
        message,
    ].join(' '));
}

function createHandler(task) {
    log(task.name, chalk.yellow('started'));
    const promise = Promise.resolve(task());

    return promise
        .then((result) => {
            log(task.name, chalk.green('done'));
            return result;
        });
}

const createParallel = (...tasks) => function parallel() {
    return Promise.all(tasks.map(createHandler));
};

const createSeries = (...tasks) => {
    const reducer = async (promiseChain, task) => {
        const chainResult = await promiseChain;
        const result = await createHandler(task);

        return chainResult.concat(result);
    };
    const reducedTasks = tasks.reduce(reducer, Promise.resolve([]));

    return function series() {
        return reducedTasks;
    };
};

module.exports = {
    parallel: createParallel,
    series: createSeries,
};