Use Class in Node.js

Introduction

Node.js is trending as an environment where different efficient and logical applications are executed at the moment. One of them is extending modern JS syntax, for example, classes, which makes OOP in Node.js more possible to use and improve. Scroll down to learn what a class is in Node.js, how one can be defined, how methods can/must be added, subclass/superclass in Node.js, and some uses of classes in Node.js.

What is a Class in Node.js?

A class is a blueprint of objects that have certain characteristics and behaviors or actions. Classes were introduced in ECMAScript 2015 ( ES6) as a way of getting a more organized way of writing Object Oriented Programming code in JavaScript.

Why Use Classes in Node.js?

Classes help in:

• Code organization: The Group related functionality for the reason of better modularity should be maintained.
• Reusability: Use subtyping to reuse of existing classes to the maximum.
• Readability: Syntax is neater than in older proto-typing approaches based on the prototype objects.
• Scalability: Especially used to solve large scale and complicated problems.

Basic Syntax of a Class

Here's a simple example of a class in Node.js:

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

  greet() {
    return `Hello, my name is ${this.name} and I am ${this.age} years old.`;
  }
}

// Usage
const person1 = new Person('Alice', 30);
console.log(person1.greet());

Output

Hello, my name is Alice and I am 30 years old.

Creating and Using Methods

Classes allow the defining of methods within them. These methods are invoked using instances of the class:

class Calculator {
  add(a, b) {
    return a + b;
  }

  subtract(a, b) {
    return a - b;
  }
}

// Usage
const calc = new Calculator();
console.log(calc.add(5, 3)); // Output: 8
console.log(calc.subtract(5, 3)); // Output: 2

Output

8
2

Inheritance in Classes

Inheritance allows a class to reuse the logic of another class using the extends keyword:

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

  speak() {
    return `${this.name} makes a noise.`;
  }
}

class Dog extends Animal {
  speak() {
    return `${this.name} barks.`;
  }
}

// Usage
const dog = new Dog('Buddy');
console.log(dog.speak()); // Output: Buddy barks.

Output

Buddy barks.

Using Classes with Modules in Node.js

Node.js involves a modular concept referring to module.exports and require . Here's how you can use classes with modules:

File: math.js

class MathOperations {
  multiply(a, b) {
    return a * b;
  }
}

module.exports = MathOperations;

File: app.js

const MathOperations = require('./math');

const math = new MathOperations();
console.log(math.multiply(3, 4)); // Output: 12

Practical Example: Building a User Model

Classes are very helpful in use cases such as the user management. Here's an example:

class User {
  constructor(username, email) {
    this.username = username;
    this.email = email;
  }

  getDetails() {
    return `Username: ${this.username}, Email: ${this.email}`;
  }
}

// Usage
const user = new User('john_doe', '[email protected]');
console.log(user.getDetails());

Output

Username: john_doe, Email: [email protected]

Conclusion

Classes in Node.js makes coding neat, well-organized, and easy to follow and read. This article offered simple instructions on creating, working with and extending classes which were supported by examples. But, with the help of this, you can easily understand how to structure your Node.js applications.