JavaScript

This page gently explains JavaScript class syntax as a blueprint for objects that share data and behavior.

class

A class is a template for creating objects with common properties and methods. For example, a Dog class can describe what every dog object stores and does, while each object can have its own name.

A basic class

class Dog {
  constructor(name) {
    this.name = name;
  }

  bark() {
    console.log(this.name + " says woof!");
  }
}

const pochi = new Dog("Pochi");
pochi.bark(); // Pochi says woof!

• class Dog { ... } defines the blueprint.
• constructor(name) runs when a new object is created and sets its initial data.
• this.name stores the name on the current object.
• bark() is a method shared by objects made from the class.
• new Dog("Pochi") creates an actual object, called an instance.

When is a class useful?

Classes are useful when many objects have the same kinds of data and actions. Do not create a class only because it is available; a small object or a function may be clearer when there is no shared structure.

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