What are Classes in JavaScript

A brief review

Let's start with a summary of what we have discussed in the past few lessons.

We know that there is a this keyword for JavaScript functions. When used in an object, it refers to the current instance of that object.

1let user = {
2  name: "John",
3  hi() {
4    console.log(`Hello, ${this.name}!`);
5  },
6};
7
8user.hi();

1Hello, John!

Unlike the this keyword in other programming languages, JavaScript allows this to exist outside of an object, which enables us to build constructor functions like this:

1function User(name) {
2  this.name = name;
3  this.hi = function () {
4    console.log(`Hello, ${this.name}!`);
5  };
6}
7
8let user = new User("John");
9
10console.log(user.name);
11user.hi();

1John
2Hello, John!

Constructor functions are used to programmatically create objects. You can create both properties and methods with a constructor function.

There are two special properties in objects called getters and setters. As the name suggests, they are used to get or set property values.