チャレンジ：クラスにメソッドを追加する

              
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class Book {
  constructor(title, author, genre) {
    this.title = title;
    this.author = author;
    this.genre = genre;
  }

  _____() {
    return `${this._____} by ${this._____} is a ${this._____} book.`;
  }

  _____(_____) {
    this._____ = _____;
  }
}

// Instance
const book1 = new Book('The Great Gatsby', 'F. Scott Fitzgerald', 'Classic');

// Test the methods
console.log(book1._____()); // Expected: The Great Gatsby by F. Scott Fitzgerald is a Classic book.
book1._____(_____); // Update genre
console.log(book1._____()); // Expected: The Great Gatsby by F. Scott Fitzgerald is a Historical Fiction book.

              
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class Book {
  constructor(title, author, genre) {
    this.title = title;
    this.author = author;
    this.genre = genre;
  }

  getInfo() {
    return `${this.title} by ${this.author} is a ${this.genre} book.`;
  }

  updateGenre(newGenre) {
    this.genre = newGenre;
  }
}

// Instance
const book1 = new Book('The Great Gatsby', 'F. Scott Fitzgerald', 'Classic');

// Test the methods
console.log(book1.getInfo()); // Output: The Great Gatsby by F. Scott Fitzgerald is a Classic book.
book1.updateGenre('Historical Fiction'); // Update genre
console.log(book1.getInfo()); // Output: The Great Gatsby by F. Scott Fitzgerald is a Historical Fiction book.