Why You Should Switch to TypeScript

JavaScript is one of the most popular programming languages, and it is undisputedly the best programming language for the web.

However, with JavaScript there are a few glaring flaws. One of the major issues is the absence of type checking makes large codebases a pain to use. TypeScript addresses this problem, and makes JavaScript a better language for everyone.

The Bad of JavaScript

Let’s take this very simple JavaScript function, add that adds two numbers and returns the sum:

const add = (a, b) => a + b;

add(1, 2); // 3
add(1, "2"); // 12...

As you can see, it’s possible to pass anything to this function. This can cause a lot of issues when the code is more complicated than just adding two numbers.

For example, if you had a function that is supposed to only take in a User object, you may write something like this:

function greetUser(user) {
  return `Hello ${user.name}!`;
}

This looks okay, until you realize that you can pass in any value to the function, including strings, numbers, etc.

TypeScript Conversion

Let’s address the issues with the code, using TypeScript.

The first example, where you are supposed to add two numbers would look like this:

const add = (a: number, b: number) => a + b;

To some JavaScript users, this may look a bit verbose, so let’s break this function down piece by piece.

TypeScript adds the number type, and in this example, we’re specifying that both a and b have to be numbers, simple enough.

The second example is a bit more complicated. While we can use inline types for the User type, we should probably put it in it’s own type for re-usability.

You can make an object type with the following syntax:

// You can use an interface
interface User {
  name: string;
  email: string;
}

// Or a type alias
type User = {
  name: string;
  email: string;
};

Now that we have our User type, we can add it to the function.

function greetUser(user: User) {
  // You also get intellisense for the `user` variable.
  return `Hello ${user.name}!`;
}

Conclusion

Overall, switching to TypeScript is a great decision in my opinion. Once you switch to TypeScript, it’s hard going back to JavaScript because of the great features TypeScript provides.

You can view more about TypeScript on their website.