Get Programming with JavaScript

Get Programming with JavaScript - Listing 9.06

Listing 9.06 - Creating multiple Planets with our constructor

var Planet = function (name, position, type) {
    this.name = name;
    this.position = position;
    this.type = type;
    this.moons = [];

    this.showPlanet = function () {
        console.log(this.name);
        console.log("Planet " + this.position + " - " + this.type);
        console.log("Moons: " + this.moons.join(', ') + ".");
    };

    this.addMoon = function (moon) {
        this.moons.unshift(moon);
    };
};

var planet1 = new Planet("Jupiter", 5, "Gas Giant");
planet1.addMoon("Io");
planet1.addMoon("Europa");

var planet2 = new Planet("Neptune", 8, "Ice Giant");
planet2.addMoon("Triton");

var planet3 = new Planet("Mercury", 1, "Terrestrial");

[ planet1, planet2, planet3 ].forEach(function (planet) {
    planet.showPlanet();
});

Further Adventures

Listing 9.06 - Creating multiple Planets with our constructor - Task 1

Add a new moon to each planet.

var Planet = function (name, position, type) {
    this.name = name;
    this.position = position;
    this.type = type;
    this.moons = [];

    this.showPlanet = function () {
        console.log(this.name);
        console.log("Planet " + this.position + " - " + this.type);
        console.log("Moons: " + this.moons.join(', ') + ".");
    };

    this.addMoon = function (moon) {
        this.moons.unshift(moon);
    };
};

var planet1 = new Planet("Jupiter", 5, "Gas Giant");
planet1.addMoon("Io");
planet1.addMoon("Europa");

var planet2 = new Planet("Neptune", 8, "Ice Giant");
planet2.addMoon("Triton");

var planet3 = new Planet("Mercury", 1, "Terrestrial");

[ planet1, planet2, planet3 ].forEach(function (planet) {
    planet.showPlanet();
});

// add new moons
planet1.addMoon("Callisto");
planet2.addMoon("Proteus");
planet3.addMoon("Secret Alien Base");

Listing 9.06 - Creating multiple Planets with our constructor - Task 2

Create a showMoons method in the Planet constructor. It should show the moons with their index.

var Planet = function (name, position, type) {
    this.name = name;
    this.position = position;
    this.type = type;
    this.moons = [];

    this.showPlanet = function () {
        console.log(this.name);
        console.log("Planet " + this.position + " - " + this.type);
        console.log("Moons: " + this.moons.join(', ') + ".");
    };

    this.addMoon = function (moon) {
        this.moons.unshift(moon);
    };

    // add a showMoons method
    this.showMoons = function () {
        console.log("Moons:");
        this.moons.forEach(function (moon, i) {
            console.log("(" + i + ") " + moon;
        });
    };
};

Listing 9.06 - Creating multiple Planets with our constructor - Task 3

Update showPlanet to use showMoons rather than join for the moons.

var Planet = function (name, position, type) {
    this.name = name;
    this.position = position;
    this.type = type;
    this.moons = [];

    this.showPlanet = function () {
        console.log(this.name);
        console.log("Planet " + this.position + " - " + this.type);
        this.showMoons();
    };

    this.addMoon = function (moon) {
        this.moons.unshift(moon);
    };

    this.showMoons = function () {
        console.log("Moons:");
        this.moons.forEach(function (moon, i) {
            console.log("(" + i + ") " + moon;
        });
    };
};

Listing 9.06 - Creating multiple Planets with our constructor - Task 4

Create a getMoon method that returns the moon at a given index.

var Planet = function (name, position, type) {
    this.name = name;
    this.position = position;
    this.type = type;
    this.moons = [];

    this.showPlanet = function () {
        console.log(this.name);
        console.log("Planet " + this.position + " - " + this.type);
        this.showMoons();
    };

    this.addMoon = function (moon) {
        this.moons.unshift(moon);
    };

    this.showMoons = function () {
        console.log("Moons:");
        this.moons.forEach(function (moon, i) {
            console.log("(" + i + ") " + moon;
        });
    };

    this.getMoon = function (index) {
        return this.moons[index];
    };
};