Welcome to the world of React! Whether you are a beginner taking your first steps into frontend frameworks, or an experienced developer looking to upgrade your skills, this tutorial will guide you through everything you need to know about React.
React (also known as React.js or ReactJS) is a free, open-source JavaScript library primarily used for building incredibly fast and interactive user interfaces (UIs). It was created by Jordan Walke, a software engineer at Facebook (now Meta), and was first deployed on Facebook's newsfeed in 2011 before being open-sourced to the world in 2013.
Unlike full-fledged frameworks like Angular, React is explicitly focused on the View layer of the Model-View-Controller (MVC) architecture. It is the premier choice for building Single-Page Applications (SPAs), where data changes over time without requiring a full page reload.
Traditional web applications directly manipulate the Document Object Model (DOM) to reflect changes in the data. However, DOM manipulation is notoriously slow and inefficient.
React solves this problem by using a Virtual DOM.
When the state of an object in a React application changes, React updates the Virtual DOM first. It then compares this updated Virtual DOM with a pre-update version (a process known as "diffing" or "reconciliation"). Finally, React intelligently updates only the exact parts of the real DOM that have changed, rather than re-rendering the entire page. This results in massive performance boosts!
One of the most common debates in the web development community is whether React is a library or a full-fledged framework. By strict definition, React is a JavaScript library, not a framework.
Frameworks like Angular provide an all-in-one solution containing routing, state management, form validation, and HTTP client modules built-in. React, on the other hand, strictly focuses on rendering the UI (the "View" in MVC). To achieve framework-like capabilities, React developers rely on external libraries from its massive ecosystem, such as:
This lightweight nature gives developers complete freedom to choose the best tools for their specific project needs, rather than being forced into a rigid structure.
To understand why React is so powerful, you need to understand its core features:
JSX is a syntax extension for JavaScript that allows you to write HTML directly alongside your JavaScript logic. While it is not mandatory to use JSX in React, it is highly recommended because it makes the code much easier to read and write. We will explore JSX deeply in the upcoming chapters.
React enforces a strict "one-way" data binding approach. Data always flows down from parent components to child components via props. This unidirectional flow ensures that changes in child components do not unexpectedly break parent components, making your applications highly predictable and easier to debug.
As mentioned earlier, the Virtual DOM is a lightweight, in-memory representation of the real DOM. By comparing the new Virtual DOM with a snapshot of the old one, React computes the most efficient way to update the browser's DOM, resulting in buttery-smooth performance.
If you are deciding which technology to learn, it helps to know how React compares to its main competitors:
While all three are excellent choices, React currently holds the largest market share and the highest number of job openings worldwide.
React is battle-tested at the highest levels of scale. Some of the world's most popular web applications are built with React, including:
React has been the most popular frontend tool for web development for several consecutive years. Here is why developers and tech giants alike choose React:
In React, you build encapsulated components that manage their own state, and then compose them to make complex UIs. Because component logic is written in JavaScript instead of templates, you can easily pass rich data through your app and keep state out of the DOM. Components are highly reusable, meaning you can write a Button component once and use it hundreds of times across your application.
React makes it painless to create interactive UIs. You simply design simple views for each state in your application, and React will efficiently update and render just the right components when your data changes. Declarative views make your code highly predictable and incredibly easy to debug.
Because React is so popular, it has a massive global community. This means that if you run into a problem, someone else has likely already solved it. There are tens of thousands of third-party packages, extensions, and tools available on NPM to accelerate your development.
React's core principles are not limited to just the web. With React Native, you can use your exact same React knowledge to build native mobile applications for both iOS and Android.
Before you dive deep into React, it is highly recommended that you have a foundational understanding of:
let/const. (Don't worry if you aren't perfectly fluent yet; we will cover essential ES6 features in the upcoming chapters!).Ready to start your journey? Let's move on to the next chapter and set up your very first React application!
Which of the following is a core feature that makes React exceptionally fast?