What Are Things I Need to Know to Start Learning React JS?

React JS is a popular JavaScript library used for building user interfaces, particularly single-page applications where user experience is key. Created by Facebook, React has become a crucial tool for front-end developers. If you’re considering diving into React JS, here’s what you need to know to get started.

What is React JS?

React JS is a library for building composable user interfaces. It allows developers to create reusable UI components that manage their own state, then compose them to make complex UIs. React is declarative, component-based, and efficient, making it a favorite among developers for building dynamic web applications.

Key Concepts to Understand


Components are the building blocks of a React application. They can be class-based or function-based and are designed to be reusable, allowing for a modular approach to building UIs.

  • Class Components: Use ES6 classes and can hold and manage their own state.
  • Function Components: Simpler and, with the introduction of hooks, can now also manage state and side effects.

JSX (JavaScript XML)

JSX is a syntax extension for JavaScript that allows you to write HTML directly within JavaScript. It makes it easier to visualize the UI structure and integrates well with React.

State and Props

  • State: An object that holds the dynamic data of a component. It is managed within the component and can change over time.
  • Props: Short for properties, props are read-only data passed from parent to child components. They help in passing data and event handlers to child components.

Lifecycle Methods

For class components, React provides lifecycle methods to manage the component’s lifecycle, from creation to updates to unmounting. Important lifecycle methods include componentDidMount, componentDidUpdate, and componentWillUnmount.

Why Learn React JS?

  1. Popularity and Demand: React is one of the most popular libraries in the web development community, and knowing it can significantly improve your job prospects.
  2. Performance: React’s virtual DOM ensures efficient updates and rendering, providing a fast user experience.
  3. Flexibility: React can be used to build both web and mobile applications, thanks to React Native.
  4. Strong Community and Ecosystem: There are numerous resources, libraries, and tools available to help you learn and work with React.

Getting Started with React JS

To start learning React JS, follow these steps:

  1. Enroll in a React JS Online Course: Structured learning can be highly beneficial. A react js online course will guide you through the basics to advanced concepts with hands-on projects.
  2. Set Up Your Development Environment: Install Node.js and npm (Node Package Manager), and use create-react-app to set up a new React project quickly.
  3. Practice by Building Projects: Start with simple projects like a to-do list or a weather app to get hands-on experience.
  4. Join the Community: Participate in React forums, attend webinars, and contribute to open-source projects to enhance your learning.
  5. Prepare for Interviews: Review common React js interview questions to test your knowledge and prepare for job opportunities.

Essential Tools and Libraries

Tool/Library Purpose
Create React App A CLI tool to set up a new React project with a standard structure
React Router A library for managing navigation in React applications
Redux A state management library often used with React for large applications
Axios A promise-based HTTP client for making API requests
Jest and Enzyme Tools for testing React components

Important Concepts for React Developers


Hooks are functions that let you use state and other React features in function components. Common hooks include:

  • useState: Manages state in function components.
  • useEffect: Manages side effects like fetching data or directly manipulating the DOM.
  • useContext: Allows you to use context for managing global state without prop drilling.

Context API

The Context API provides a way to share data across the component tree without passing props down manually at every level. It is useful for managing global state, themes, and settings.


Learning React JS can open up numerous opportunities in web development. Start by enrolling in a react js online course to build a solid foundation. Practice regularly by working on projects and join the vibrant React community to stay updated and get support. Preparing for job opportunities by reviewing React js interview questions will help solidify your understanding and give you confidence in your skills. Happy coding!