What is React?

React is a widely distributed JavaScript library that is used for building user interfaces (UIs) by most JavaScript developers. It was created by Facebook (Meta) in 2013, and when it was published, it became one of the most widely used front-end libraries in the web development world.

With vanilla JavaScript (traditional JavaScript without frameworks or libraries), you can manually update the DOM (which can get messy and time-consuming). React lets you build reusable UI components that automatically update and change when your data changes.

React JS gives you the ability to use components together, and it makes coding easy by giving you the ability to reuse your components. Also, React JS doesn’t prescribe how to do routing and data fetching.

React JS has many advantages The most important pro of it is that with React JS you can break your UI into small, reusable pieces (components). The huge ecosystem of React JS, for example, has a large community. Also, it has many libraries and frameworks, e.g., React Router and Redux.

React JS makes DOM updates fast & efficient, and this feature saves a lot of time.

React JS Vs. Vanilla JS

As a new React learner, you want to ask, why use React instead of vanilla JavaScript?, Let's answer this question with an example of building a house:

Using vanilla JavaScript without frameworks and libraries, hammering every nail manually (tedious, error-prone).

While when using React JavaScript, it's like you use power tools (faster, organized, scalable).

Benefits of React

  • Reusable components
  • Huge ecosystem
  • Easier state management with no more spaghetti code.
  • Better performance with Virtual DOM minimizes slow updates.

Real-World Examples of React

React is used by professional companies, e.g., Facebook, Instagram and WhatsApp Web

How Does React Work?

React follows a component-based architecture.

  • You create components (imagine it as Lego blocks).
  • These components manage their own state/data.
  • When data changes, React efficiently updates only what’s needed, and that is because of the virtual DOM.

Simple Example:

javascript
          function Welcome() {
  return <h1>Hello, React Learner!</h1>;
}

This code is a functional component; also, it returns JSX (HTML-like syntax inside a JavaScript code snippet).

What You’ll Learn in This Course

In this fully free course. We will take you from scratch to advanced React concepts, covering:

  • Fundamentals: Components, Props and State
  • Hooks: useState, useEffect, etc.
  • React Router
  • State Management: Context and Redux
  • Real Projects e.g., Todo Application and API-based apps

Exercise

To start understanding React JS components, think about a Facebook post. How can we use components in it? (Meaning how we can break the Facebook post into small components?)

Solution

A Facebook post = Profile Pic + Username + Content + Like Button → Each item could be a separate React JS component.