React is a popular JavaScript library (not a framework) for building user interfaces and is used by some of the largest and well-known organizations globally, including Facebook, Instagram, and Netflix. React is known for its performance, flexibility, and ease of use. React is relatively easy to learn, especially for developers who already know JavaScript. Because it is great for building large, complex applications that need to be performant and scalable, React has become THE tool to for web developers to learn.
To help you get started with React, one of our seasoned trainers and React experts answered some of the most frequently asked questions developers have about React. For online or in-person courses, browse our React Training offerings for beginners or experienced developers.
1. What are the features of React?
Some features of React include:Declarative UI: React uses a declarative approach to building user interfaces. Declarative means you describe what you want the UI to look like rather than how you want it to be built, making code more readable and maintainable.
- Virtual DOM: React uses a virtual DOM to represent the state of the UI. This allows React to find changes between the virtual DOM and the real DOM and then only update the real DOM when necessary, resulting in better performance.
- One-way data flow: React uses a one-way data flow to manage the state of the UI. This means that changes to the state are propagated down to the UI, but changes to the UI do not affect the state, helping to prevent errors and make the code easier to reason about.
- Reusable components: React components are small, reusable chunks of code that when combined create complex UIs, making code more modular and easier to maintain.
2. What is the virtual DOM?
The virtual DOM (Document Object Model) represents the real DOM that is stored in memory. React uses the virtual DOM to detect changes in the DOM tree, then updates the real DOM when necessary. This results in better UI performance.
3. Should I build my React applications in JavaScript or TypeScript?
JavaScript is a popular and well-known language that is easy to learn and use. All web browsers and development tools also support it. However, JavaScript is not a statically typed language, which can lead to errors and unexpected behavior that can only be discovered at run-time.
TypeScript is a superset of JavaScript that uses static typing, meaning the compiler can check your code for errors at compile time. This can help to prevent bugs and improve code quality. All TypeScript is compiled into JavaScript, so it has the same level of support in web browsers.
Therefore, TypeScript is preferred for all React projects.
4. What are the differences between class-based components and functional components with hooks?
Hooks enable functional components to maintain state between renders like class-based components. Class-based components preserve state because a component instance is created. Therefore, the same component instance is used between renders. The reusing of the component instance is why class-based components have lifecycle methods.
Modern versions of React support hooks because a fiber node is used in place of a class-based instance to remember the state between renders. The functional components hook into the fiber node to retrieve the state between renders. The addition of fiber nodes to React many years ago enabled hooks, resulting in class components falling out of favor and functional components becoming more popular.
5. Do Hooks replace Redux?
No, React Hooks do not replace Redux. They are two separate things that serve different purposes.
Hooks enable the use of stateful data within React functional components. Previously, only more complicated class-based components could have stateful data. State data within React components is for components-level state only.
Redux is a state management library allowing you to store and manage application state external to the component tree. In addition to being a code library, Redux represents an entire set of concepts and principles about how an application manages its state.
Generally, the React-Redux library makes its state available via context on the React component tree. Then using hooks, that Redux state is retrieved from the context.
People often mistake the roles of hooks, context, and state and mistakenly think they are alternatives to Redux and other application state managers.
6. Why use React instead of other frameworks like Angular?
There are many reasons to use React instead of other frameworks, like Angular. Some of the key reasons include:
- React is only a UI library, while Angular is an opinionated UI framework. With React, programmers have more freedom to create a UI application, whereas Angular locks programmers into a more rigid framework.
- React works well for web and native applications. While Angular can be used for both platforms, it is generally used for web applications only.
- TypeScript must be used for Angular applications, whereas React can be programmed in JavaScript and TypeScript.
Written by Eric Greene, a professional software developer and trainer specializing in JavaScript/TypeScript technologies like React, DevOps, Azure, C#, Python, HTML, CSS, and more. He has been developing software and delivering training classes for 26 years. He holds many Microsoft certifications, including DevOps Engineer Expert, Azure Administrator Associate, and Azure Developer Associate.
