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Basics of React.js

React is a JavaScript library for building user interfaces, developed and maintained by Facebook. Widely used for its efficiency and flexibility in creating complex, interactive web applications, React allows developers to build encapsulated components that manage their own state and compose them to create complex UIs. This article explores about Basics of React.js.


2011: The Birth of React

React’s origins date back to 2011 when Jordan Walke, a software engineer at Facebook, created the initial prototype. React was developed to address Facebook’s growing need for a more efficient way to build dynamic and interactive user interfaces. The early version of React was internally used within Facebook, particularly in the Facebook Ads system, to improve the performance and maintainability of their front-end code.

Public Release

2013: Open Source Release

Facebook open-sourced React at the JavaScript conference JSConf US in May 2013.┬áThis release introduced the broader development community to React’s component-based architecture and its innovative approach to rendering and updating user interfaces efficiently.

Key features introduced in the initial public release:

  • Component-Based Architecture: Encourages reusable UI components.
  • Virtual DOM: A lightweight representation of the actual DOM that improves performance by minimizing direct manipulations of the DOM.
2014: React Native Announcement

In January 2014, Facebook announced React Native, a framework for building native mobile applications using React. React Native aimed to bring the same declarative UI paradigm and efficiency of React to mobile development, enabling developers to write mobile applications for iOS and Android using JavaScript and React.

Key Concepts of React


React is based on the concept of components. Developers can reuse components as pieces of UI that can be nested, managed, and handled independently. Components can be functional or class-based:

Basics of React.js

Functional Components: These are simple functions that return React elements. They are also known as stateless components.

Class Components: These are ES6 classes that extend React. Component and can hold and manage their own state.


JSX, or JavaScript XML, is a syntax extension for JavaScript that looks similar to XML or HTML. Furthermore, it allows developers to write HTML elements directly within JavaScript.

Basics of React.js

JSX eases the visualization of the structure of UI components, albeit it requires transpilation into JavaScript using tools like Babel.


State is an object that determines how a component renders and behaves. Moreover, the component manages it within and can change over time, usually in response to user actions.


Props (short for properties) are read-only attributes that the parent components pass to the child components. Consequently, they allow data to flow from the parent component to the child component.

Lifecycle Methods

Class components in React have several lifecycle methods that allow developers to hook into different phases of a component’s lifecycle, such as:

componentDidMount(): The system renders the component for the first time.

componentDidUpdate(prevProps, prevState): Called after the component updates due to changes in state or props.

componentWillUnmount(): The system removes the component from the DOM.

Handling Events

React handles events similarly to HTML but uses camelCase for event names and passes the event handler as a function:

Conditional Rendering

React allows conditional rendering using JavaScript conditional operators:

Lists and Keys

Rendering lists in React involves using the map() function to create an array of elements. Additionally, keys are used by React to identify which items have changed, are added, or are removed.

Advanced Features

Context API

The Context API provides a way to pass data through the component tree without having to pass props down manually at every level. Consequently, it is useful for global state management.

React Hooks

Introduced in React 16.8, hooks allow functional components to utilize state and other React features effectively.

Basics of React.js

useState: For state management in functional components.

useEffect: For performing side effects in functional components.

useContext: For accessing the context API in functional components.


Basics of React.js: React is a powerful and flexible library for building user interfaces. With its component-based architecture, JSX syntax, and advanced features like hooks and the Context API, React simplifies the development of complex and interactive web applications. Moreover, understanding its core concepts and advanced features allows developers to create efficient, maintainable, and scalable applications.

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