JavaScript Classes

Understanding the Fundamentals and Modern Syntax

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Classes are a fundamental concept in object-oriented programming that model real-world objects by bundling together related properties and functionality.

While JavaScript has always been prototype-based without true classes, recent syntax additions make defining classes and creating instances straightforward similar to traditional class-based languages.

In this article, we’ll explore the basics of JavaScript classes — how they work under the hood, their syntax features, and how to use them properly. We’ll also go over some best practices when working with JS classes in modern code.

Defining a Basic Class in JavaScript

At its core, a class defines a blueprint for creating objects with a common structure and behavior. Here is a simple User class example:

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

  sayHi() {
    console.log(`Hello, my name is ${this.name}!`); 
  }
}

const me = new User('John');
me.sayHi(); // logs "Hello, my name is John!"

We define the class with the class keyword followed by the name of the class (User). Inside the class, there is a special constructor() method that initializes each new instance when we call new User()…