Javascript worker queue problem.

question.md

new Worker().eat().sleep(2).work().sleep(2).eat().work()

Get this to print

eat
// wait for 2 seconds
work
// wait for 2 seconds
eat
work

worker1.js

// This solution with block the event-loop => only 1 worker can run at a time

class Worker {
    
    sleep(second) {
        const time = Date.now();
        while (Date.now() - time < second * 1000) {
        }
        return this;
    }
    
    eat() {
        console.log('eat')
        return this;
    }
    
    work() {
        console.log('work')
        return this
    }
}

new Worker().eat().sleep(2).work().sleep(2).eat().work()

worker2.js

// This solution make use of the macro-queue of Web Timer, multiple worker can run at a time

class Worker2 {
    queue = []

    constructor() {
        setTimeout(async () => {
            for (const job of this.queue) {
                await new Promise(resolve => setTimeout(() => {
                    job[0]()
                    resolve()
                }, job[1] * 1000))
            }
        }, 0)
    }

    sleep(second) {
        this.queue.push([() => {}, second])
        return this
    }

    eat() {
        this.queue.push([() => console.log('eat'), 0])
        return this
    }

    work() {
        this.queue.push([() => console.log('work'), 0])
        return this
    }
}

new Worker2().eat().sleep(2).work().sleep(2).eat().work()

worker3.js

// This solution make use micro-queue of promises (higher priority than macro-queue), multiple worker can run at a time

function Worker3() {
    this.taskQueue = Promise.resolve();
    
    this.addTask = f => {
        this.taskQueue = this.taskQueue.then(f);
    }
    
    this.sleep = function(timer) {
        this.addTask(() => new Promise((resolve, reject) => {
            setTimeout(() => {
                resolve();
            }, timer * 1000);
        }))
        return this;
    }
    
    this.eat = function() {
        this.addTask(() => console.log('eat'));
        return this;
    }
    
    this.work = function() {
        this.addTask(() => console.log('work'));
        return this;
    }
}

new Worker3().eat().sleep(2).work().sleep(2).eat().work()

worker4.js

// Simple solution by treating sleepDuration as a queue

class Worker4 {

    sleepDuration = 0

    sleep(second) {
        this.sleepDuration += second * 1000
        return this
    }

    eat() {
        setTimeout(() => console.log('eat'), this.sleepDuration)
        return this
    }

    work() {
        setTimeout(() => console.log('work'), this.sleepDuration)
        return this
    }
}

new Worker4().eat().sleep(2).work().sleep(2).eat().work()