JavaScript Class

In JavaScript, a class is a structured way to define how objects should behave. It provides a reusable blueprint for creating multiple objects with similar properties and functions. Classes are part of Object-Oriented Programming (OOP) and are useful in organizing and scaling your code.

What Is a Class?

A class groups together data (properties) and functions (methods) into a single unit. This structure helps you create multiple objects that follow the same pattern without rewriting code.

Defining a Class

You can define a class using the class keyword. Inside the class, the constructor() method is used to initialize object properties:

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

The constructor runs automatically when a new object is created using the class.

Creating Objects from a Class

To create an object, use the new keyword followed by the class name:

				
					let person1 = new Person("Arshyan", 22);
let person2 = new Person("Ali", 18);

Now both objects have their own name and age values, but share the same structure.

Adding Methods to a Class

Classes can also contain methods—functions that belong to every object created from the class.

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

  greet() {
    return `Hello! I'm ${this.name}, and I'm ${this.age} years old.`;
  }
}

let p = new Person("Hamza", 28);
console.log(p.greet());

This will output:

				
					Hello! I'm Hamza, and I'm 28 years old.

Why Use Classes?

Repetitive work minimal – Create many objects from one definition.
Organized – Keep related properties and methods in one place.
Easier to manage – Especially in large projects.

Inheritance

JavaScript classes support inheritance, which allows one class to extend another and reuse its code. For example:

				
					class Student extends Person {
  constructor(name, age, grade) {
    super(name, age); // Call parent constructor
    this.grade = grade;
  }

  info() {
    return `${this.name} is in grade ${this.grade}.`;
  }
}

The Student class inherits from Person and adds a new grade property.

Key Points

Use class to define a blueprint for objects.
The constructor() sets up the initial values.
Add methods inside the class to define behavior.
Use new to create an object from the class.
Inheritance allows reuse and extension of class functionality.