What is ReactJS & Why Is It So Popular?

ReactJS, usually just called React, is a JavaScript library for building user interfaces. React was developed to build the front end of a website. It is the most popular framework of its kind.

React can be combined with other libraries to create entire applications for the web, mobile devices, or Windows desktop. It’s owned and maintained by Facebook but it remains open-source and free.

Let’s take a deeper dive into React. What is it? Who uses it? Why should you learn it? Read on to find out all of this and more!

What is React?

ReactJS, usually just called React, is a JavaScript library for building user interfaces. More simply put, React was developed to build the front end of a website. It’s the most popular framework of its kind.

React is declarative which means a smaller codebase for the same functional yield of a non-declarative library. Declarative code is simply that is formatted in a way that allows the developer to tell the library what to do, not how to do it.

React apps are built one encapsulated component at a time which manages their own state and stack hierarchically to build out an entire UI. This in combination with React’s declarative nature makes debugging faster and easier.

React can be combined with other libraries to create entire applications for the web, mobile devices, or Windows desktop. It’s used by multinational corporations, social media empires, sharing economy applications, and more.

What is a library?

A library is a chunk of prewritten, reusable code that you can use to build your JavaScript application or website more efficiently. They can be used alongside JavaScript frameworks to make a complete app quickly and easily.

A framework is like a blueprint while a library is more like a module. They’re both chunks of reusable code that are secure and standard. Sometimes the words library and framework are used interchangeably.

You can consider a framework a house, it can be used to create a whole app from foundation to ceiling. A library can be compared to the appliances and furniture inside the house. They make using JavaScript faster and more secure because developers don’t have to code everything from scratch. Developers order these components in a logical way to create a larger, more complex application.

How does React work?

React is a JavaScript library that creates user interfaces (UIs) in a structured and efficient way using declarative code. React allows developers to build an application’s UI one self-contained component at a time. Components are basically chunks of reusable code that declare which react component appears on the screen.

What is React Used for?

React is used for creating the user interface (UI) of a website or web application. React has been used to build newspaper websites, blogs, social media, shopping apps, fintech applications, sharing economy platforms, SaaS tools, and more.

React was designed to be used for web applications that were built with JavaScript. But it can be used to create applications across almost any platform. ReactDOM can be used for web applications. React Native can be used to develop mobile applications and provide one codebase for both iOS and Android applications. Cross-platform hybrid desktop applications can pair React and Electron or React Native for Windows.

React is versatile. It can build the whole UI or just one UI component. This includes the visual elements, binding data to those elements, and specifying the logic governing them. React could also lay the groundwork for a more complex application in combination with other libraries and frameworks Material-UI, Next, Express, Mongoose, MongoDB, Redux, and more.

Who uses React?

Major multinational companies are using React to build their web apps. From social media to sharing economy platforms to news organizations, you’ll find React powering the most popular user interfaces on the web.

Learn more about how each company uses React:

Why use React?

Like many of the most popular frameworks and libraries, React is efficient, enables rapid development, and it’s scalable to power a massive web application. It was developed by Facebook in 2013 and they still maintain it.

When React is used to build an app in combination with other libraries or technologies, it's compatible with their older versions thanks to the vigilant maintenance from Facebook. The React community is massive, supported, and the framework is continuously being updated. React offers more than most libraries. You’ll find tools, libraries, and approaches to be used as a custom framework or just a toolset to build specific components.

It’s versatile enough to be used for applications on nearly any platform with the help of React Native, ReactDOM, React Native for Windows, and Electron. It can also lay the groundwork for a more complex application in combination with other libraries and frameworks Material-UI, Next, Express, Mongoose, MongoDB, GraphQL, Relay, Redux, and more.

React is declarative which makes it more approachable for developers and more lightweight. Simply put, when building a declarative app, the developer tells the app what should be displayed instead of the steps it needs to take to display it.

React is fast, scalable, and secure. It’s the perfect library for a modern, agile software design that is easy to update. Minimum viable products (MVPs) can be created rapidly and already built apps can be scaled quickly thanks to React’s modular component design.

What you need to know before learning React

To use React, you must be proficient in JavaScript, understand the ES6 syntax, using Git, the command line (Terminal for Mac or Bash or Windows), and understand the process of building a web application. You should also know HTML and CSS. JSX and Babel will go a long way with React as well.