function Book(title, author, year){
    this.title = title;
    this.author = author;
    this.year = year;

}

const book1 = new Book('Snow', 'Jon Snow', '2017');

Book.prototype.getSummary = function() {
    return `${this.title} was written  by ${this.author} in ${this.year}`;
}

Book.prototype.getAge = function() {
    const years = new Date().getFullYear() - this.year;
    return `${this.title} is ${years} years old`;
};

Magazine.prototype = Object.create(Book.prototype);

function Magazine(title, author, year, month){
    Book.call(this, title, author, year);
    this.month = month;
}



const mag1 = new Magazine('Magi', 'Joel Tim', '2018', `Jan`);



const bookProtos = {
    getSummary: function() {
        return `${this.title} was written  by ${this.author} in ${this.year}`;
    },
    getAge: function() {
        const years = new Date().getFullYear() - this.year;
        return `${this.title} is ${years} years old`;
    }
};

const book3 = Object.create(Book.prototype);
book3.title = 'Book One';
book3.author = 'OneM';
book3.year = '2015';

const book3 = Object.create(bookProtos, {
    title: {value: 'Book One'},
    author: {value: 'OneM'},
    year: {value: '2015'}
});