A song of "Grandfather's Clock" as a javascript source code.

grandfathers-clock.js

/***************************************************************************
Copyright (c) 2017 tatsuo watanabe<[email protected]>

Permission is hereby granted, free of charge, to any person obtaining a copy
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****************************************************************************/

/**
 * Tick the lifetime
 */
class TickTockable {
  constructor(opts) {
    const options = opts || {};
    this.duration = options.duration || 1000;
    this.narrator = options.narrator || console.log;
    this.age = 0;
    this.isBorn = false;
    this.isAlive = true;
    this.promise = new Promise((resolve) => { this.resolve = resolve; });
  }
  /** Tick the time. */
  tick() { this.alive(() => this.tock()); const s = this.sound('tick'); if (!s) { return; } this.narrator(s); }
  /** Tock the time. */
  tock() { this.alive(() => this.tick()); const s = this.sound('tock'); if (!s) { return; } this.narrator(s); }
  /** Variety of somethig will affair. */
  affair() { this.narrator('Variety of somethig will affair.'); }
  /** There are many things if you live. */
  alive(callback) {
    if (!this.isAlive) { return; }
    if (this.isBorn)   { this.age += 1; }

    this.affair();
    setTimeout(() => {
      callback();
    }, this.duration);
  }
  /** Sounds of your story. */
  sound(key) {
    const sounds = { tick: 'tick...', tock: 'tock...' };
    return sounds[key];
  }
  rnd(accuracy) {
    return Math.ceil(Math.random() * accuracy) === accuracy;
  }
}

class Oldman extends TickTockable {
  constructor(clock, opts, name) {
    super(opts);
    this.name   = name;
    this.clock  = clock;
    this.isBorn = false;
    this.alive(() => this.tick());
  }
  sound() {
    const footstep = !this.isBorn    ? 'throb...'  : 
                     this.age <    3 ? 'mewl...'   :
                     this.age === 13 ? 'giggle...' :
                     this.age === 17 ? 'yeah...'   :
                     this.age === 24 ? 'you are my pleasure...' :
                     this.age === 75 ? 'what a faithful clock...' :
                     '';
    return footstep;
  }
  affair() {
    this.born();
    this.marry();
    this.babyBorn();
    this.grandChildBorn();
    this.die();
  }
  born() {
    if (this.isBorn)   { return; }
    if (!this.rnd(10)) { return; }
    this.isBorn = true;
    this.clock.owner = this;
    this.narrator(`${this.name} was born.`);
  }
  marry() {
    if (this.age !== 24 || this.married) { return; }
    this.married = true;
    this.narrator(`Blooming and beautiful bride came.`);
  }
  babyBorn() {
    if (this.age !== 30 || this.hasChild) { return; }
    this.hasChild = true;
    this.narrator(`${this.name} had a baby born.`);
  }
  grandChildBorn() {
    if (this.age !== 60 || this.hasGrandchild) { return; }
    this.hasGrandchild = true;
    this.narrator(
      `${this.name} had a grandchild born.\nI was born.`
    );
  }
  die() {
    if (this.age < 90) { return; }
    this.isAlive = false;
    setTimeout(() => {
      this.narrator(`${this.name} was died.`);
      this.resolve();
    }, this.duration * 2);
  }
}

class Clock extends TickTockable {
  constructor(opts) {
    super(opts);
    this.isBorn   = true;
    this.isBought = false;
    this.owner    = undefined;
    this.alive(() => this.tick());
  }
  affair() {
    this.bought();
    this.die();
  }
  bought() {
    if (!this.owner || this.isBought) { return; }
    this.isBought = true;
    this.narrator(`The clock was bought for ${this.owner.name}.` );
  }
  die() {
    if (!this.owner || this.owner.isAlive) { return; }
    this.isAlive = false;
    setTimeout(() => {
      this.narrator(`The clock stopped short, never to go again.`);
      this.resolve();
    }, this.duration * 2);
  }
}

/**
 * "Grandfather's Clock" is a song written in 1876 by Henry Clay Work,
 * the author of "Marching Through Georgia". 
 * It is a standard of British brass bands and colliery bands,
 * and is also popular in bluegrass music.
 * It has also been sung by male choruses such as the Robert Shaw Chorale.
 * --- From Wikipedia, the free encyclopedia
 * 
 * @see https://en.wikipedia.org/wiki/My_Grandfather's_Clock
 */
function myGrandfathersClock(opts) {
  const options = opts || {};
  options.narrator = options.narrator || console.log;
  options.duration = options.duration || 1000;
  const narrator    = options.narrator;
  const clock       = new Clock(options);
  const grandfather = new Oldman(clock, options, 'My grandfather');
  Promise.all([
    clock.promise,
    grandfather.promise
  ]).then(() => 
    setTimeout(() => narrator('I remember you.'), options.duration)
  );
}

myGrandfathersClock();