Modi diversi di definire oggetti e classi in js

classes_and_objects.js

'use strict';


// oggetto semplice
var book1 = {
    title: "The Handmaid's Tale",
    author: "Margaret Atwood",
    year: 1985,
}

console.log(book1.title); 
console.log(book1);


// oggetto definito tramite una funzione (vecchio stile)
function Book(title, author, year) {
    this.title = title;
    this.author = author;
    this.year = year;
}

var book2 = new Book("The Ice People", "Maggie Gee", 1999);

console.log(book2.title); 
console.log(book2);

// definizione di metodi tramite il prototipo
Book.prototype.setYear = function(year) {
    this.year = year;
}

book2.setYear(2000);

console.log(book2.year); 

// classe (ECMA6)
class Person {
    constructor (firstName, lastName, age) {
        this.firstName = firstName;
        this.lastName = lastName;
        this.age = age;
    }
    setAge(age) {
        this.age = age;
    }
}

var ma = new Person("Margaret Atwood", "Margaret Atwood", 79);

console.log(ma);

ma.setAge(80);
console.log(ma);

// classe derivata
class Author extends Person {
    constructor(firstName, lastName, age) {
        super(firstName, lastName, age);
        this.books = [];
    }
    addBook(book) {
        if (!book.author) {
            book.author = this.getFullName();
        }
        this.books.push(book);
    }
    getFullName() {
        return `${this.firstName} ${this.lastName}`;
        // return [this.firstName, this.lastName].join(" ");
    }
}

var mg = new Author("Maggie", "Gee", 2019-1948);

mg.addBook(book2);
console.log(mg);
mg.addBook(new Book("Light Years", null, 1985));
console.log(mg);


// classe con getter e setter
class Bus {
    constructor(id, plate) {
        this._id = id;
        this._plate = plate;
    }
    
    get id() {
        return this._id;
    }
    
    set id(value) {
        this._id = value;
    }

    get plate() {
        return this._plate;
    }
    
    set plate(value) {
        this._plate = value;
    }

    get seats() {
        return this._seats;
    }
    
    set seats(value) {
        this._seats = value;
    }
    
}

let b1 = new Bus(3, "FG003DK");
b1.seats = 30;
console.log(b1.seats);

// classe con accesso agli attributi in stile jQuery
class Sensor {
    constructor(id) {
        this._id = id;
        this._value = 0;
    }
    value(v) {
        if (v!==undefined) {
            this._value = v;
            return this;
        }
        else {
            return this._value;
        }
    }
    color(v) {
        if (v!==undefined) {
            this._color = v;
            return this;
        }
        else {
            return this._color;
        }
    }
}

let s = new Sensor(67);
s.value(80).color("red");
console.log(s.value());