Constructors in classes in Javascript - Mini Project: Build & Apply

Constructors in Classes

📖 Scenario: You are creating a simple program to keep track of pets in a pet store. Each pet has a name and an age.

🎯 Goal: Build a class called Pet that uses a constructor to set the pet's name and age. Then create a pet object and display its details.

📋 What You'll Learn

Create a class named Pet

Add a constructor method with parameters name and age

Inside the constructor, assign name and age to the object properties

Create an instance of Pet with name Buddy and age 3

Print the pet's name and age using the instance

💡 Why This Matters

🌍 Real World

Classes with constructors are used to create objects that represent real things, like pets, users, or products, with their own data.

💼 Career

Understanding constructors is essential for building organized and reusable code in many programming jobs, especially in web development.

1

Create the Pet class

Write a class called Pet with an empty constructor method.

Javascript

class Pet {
  constructor() {
    // Your code here
  }
}

Need a hint?

Use the class keyword followed by Pet. Inside, add constructor() with empty braces.

2

Add parameters and assign properties in the constructor

Modify the constructor to accept parameters name and age. Inside the constructor, assign this.name = name and this.age = age.

Javascript

class Pet {
  constructor(name, age) {
    // Your code here
  }
}

Need a hint?

Inside the constructor, use this.name = name and this.age = age to store the values.

3

Create a Pet instance

Create a variable called myPet and assign it a new Pet object with name "Buddy" and age 3.

Javascript

class Pet {
  constructor(name, age) {
    this.name = name;
    this.age = age;
  }
}

// Your code here

Need a hint?

Use new Pet("Buddy", 3) to create the object and assign it to myPet.

4

Print the pet's name and age

Write a console.log statement to print myPet.name and myPet.age separated by a space.

Javascript

class Pet {
  constructor(name, age) {
    this.name = name;
    this.age = age;
  }
}

const myPet = new Pet("Buddy", 3);

// Your code here

Need a hint?

Use console.log(myPet.name + " " + myPet.age) to print the values.