minimal task runner

task.js

#!/usr/bin/env node
const _tasks = {}

function task (name, fn) {
    _tasks[name] = fn
}

task.run = async function (name, wait) {
    if (!name) return console.warn(`Usage: node task [name]`)
    if (!_tasks[name]) return console.warn(`No task named ${name}`)
    console.info(`> Running task: ${name}`)
    return wait ? await _tasks[name].call() : _tasks[name].call()
}

task.parallel = function (tasks) {
    for (const t of tasks) task.run(t)
}

task.series = async function (tasks) {
    for (const t of tasks) await task.run(t)
}

const say = (str, time) => new Promise(resolve => setTimeout(_ => resolve(console.log(str)), time))

task('scripts', async function () {
    await say('A', 200)
})

task('styles', async function () {
    await say('B', 100)
})

task('xxx', async function () {
    await say('C', 300)
})

task('yyy', async function () {
    await say('D', 100)
})

task('build', async function () {
    await task.run('scripts') // A
    await task.run('styles') // B
    await task.parallel(['scripts', 'styles']) // B, A
    await task.series(['xxx', 'yyy']) // C, D
})

task.run(process.argv[2])