TypeScript Doesn’t Turn JavaScript Into a Class-Based OOP Language

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TypeScript is just a natural extension of JavaScript. It doesn’t turn it into a new language. Rather, it just adds type annotations and checking to exist JavaScript code.

In this article, we’ll look at why TypeScript isn’t a class-based OOP language.

TypeScript Classes Aren’t Classes

A TypeScript class is just a JavaScript class with some data type annotations and generic data types markers added to it.

However, those are just add-ons to a JavaScript class, which is just syntactic sugar on top of constructor functions.

For instance, if we have the following JavaScript class:

class Foo {
    name: string;
    constructor(name: string) {
        this.name = name;
    }
}

We see that when we log the type of the Foo class as follows:

console.log(typeof Foo)

We see that it’s a function. It’s no different from the regular JavaScript class, which is just a constructor function.

Underneath, the constructor is just assigning items to this from the function parameters. And instance methods are just properties of the prototype of the function.