Why you should use TypeScript for your React projects

TypesScript is a typed JavaScript superset created by Microsoft, that gets compiled into JavaScript. You don't need to use it in all your scripts, which means you can migrate your codebase as slowly as you want, or simply start writing your new files using TypeScript.

I think it's fair to say TypeScript has gained a lot of momentum in the last few years, but it's still not the default for many frameworks and libraries, even though most of the community is adopting it.

Let's dive into the main point: why should you use TypeScript, taking into account that most of the time that means having more code? Take a look at the following example:

import React, { ReactDOM } from 'react' 

const Greeting = (props) => {
  return (
    <p>Hello, my name is {props.name} and I'm {props.age} years old.</p>
  )
}

ReactDOM.render(
  <Greeting name="Roger" age={30} />,
  document.getElementById('example')
);

This is a really simple component in JavaScript, but it will be enough to make my point. The same component could be written in TypeScript as follows:

import React, { ReactDOM } from 'react' 

interface Props {
  name: string
  age: number
}

const Greeting = (props: Props) => {
  return (
    <p>Hello, my name is {props.name} and I'm {props.age} years old.</p>
  )
}

ReactDOM.render(
  <Greeting name="Roger" age={30} />,
  document.getElementById('example')
);

Both components do exactly the same, but in TypeScript we have typed props, with both name and age defined and typed.

The issue with the JavaScript one is that it would accept all of these:

<Greeting name="Roger" /> // output "Hello, my name is Roger and I'm  years old"
<Greeting age={30} /> // output: "Hello, my name is  and I'm 30 years old"
<Greeting /> // output: "Hello, my name is  and I'm  years old"

Not to mention other consequences when using more complex types like objects or functions, which can lead to crashes or errors/warnings in the developer console.

Typescript will help you know much better which props you need to pass to a component, which ones are optional, and last but not least, the types of these props. All of these, added to the extra type safety on regular functions, will make your development process much faster and more reliable. IDEs understand it better than plain JavaScript in most situation and can help when refactoring components or functions.

It may not seem necessary for small components like this, but when your codebase has tens, hundreds, or thousands of interrelated components it is truly priceless.

Quick note about PropTypes

An alternative to have some kind of type validation in React props using JavaScript is the prop-types library. You can read more about that here. The problem with that is that only verifies props, not other variables used in non-component functions.

In my opinion, it was a good solution when TypeScript wasn't mature enough, but nowadays it's not worth it.

Further reading