JavaScript_ Build a Library

3種類のメディア(book、movie、cd)は、以下の属性と方法を有する.

class Media {
  constructor(title) {
    this._title = title;
    this._isCheckedOut = false;
    this._ratings = [];
  }

  get title() {
    return this._title;
  }

  get isCheckedOut() {
    return this._isCheckedOut;
  }

  get ratings() {
    return this._ratings;
  }

  set isCheckedOut(value) {
    this._ischeckedOut = values; 
  }

  toggleCheckOutStatus() {
    this._isCheckedOut = !this._isCheckedOut;
  }

  getAverageRating() {
    let ratingSum = this._ratings.reduce((accumulator, rating) => accumulator + rating);
    return ratingSum / this.ratings.length;
  }

  addRating(value) {
    this._ratings.push(value);
  }
}

//creating Book class
class Book extends Media {
  constructor(author, title, pages) {
    super(title); //  Pass it any arguments that the parent constructor uses
    this._author = author;
    this._pages = pages;
  }
  get author() {
    return this._author;
  }
  get pages() {
    return this._pages;
  }
}

// creating Movie class
class Movie extends Media {
  constructor(director, title, runTime) {
    super(title);
    this._director = director;
    this._runTime = runTime;
  }
  get director() {
    return this._director;
  }
  get pages() {
    return this._pages;
  }
}

// historyOfEverything
const historyOfEverything = new Book('Bill Bryson', 'A Short History of Nearly Everything', 544);

historyOfEverything.toggleCheckOutStatus();
console.log(historyOfEverything.isCheckedOut);

historyOfEverything.addRating(4);
historyOfEverything.addRating(5);
historyOfEverything.addRating(5);
console.log(historyOfEverything.getAverageRating());


// speed
const speed = new Movie('Jan de Bont', 'Speed', 116);

speed.toggleCheckOutStatus();
console.log(speed.isCheckedOut);

speed.addRating(1);
speed.addRating(1);
speed.addRating(5);

console.log(speed.getAverageRating());

// creating CD
class CD extends Media {
  constructor(singer, title, track) {
    super(title);
    this._singer = singer;
    this._track = track;
  }
  get singer() {
    return this._singer;
  }
  get track() {
    return this._track;
  }
}

const timeless = new CD('Gemma Brown', 'Sunny day', 8);

timeless.toggleCheckOutStatus();
console.log(timeless.isCheckedOut);

timeless.addRating(2);
timeless.addRating(4);
timeless.addRating(5);

console.log(timeless.getAverageRating());