REACT INTRODUCTION

React Introduction

             ReactJS is a declarative, efficient, and flexible JavaScript library for building reusable UI components. As an open-source, component-based front-end library, it focuses solely on the view layer of applications. Created by Jordan Walke, a software engineer at Facebook, ReactJS was first developed for Facebook’s newsfeed in 2011 and later used in its products like WhatsApp and Instagram. It was publicly released in May 2013.

             Today, many websites are built using the MVC (Model-View-Controller) architecture. In this architecture, React serves as the 'V' for View, while Redux or Flux handle the architecture and state management.

              A ReactJS application consists of multiple components, each components responsible for rendering a small, reusable piece of HTML. These components are fundamental to React applications and can be nested within each other, enabling the creation of complex applications from simple building blocks. ReactJS employs a virtual DOM mechanism to update the HTML DOM efficiently, as it only modifies individual DOM elements rather than reloading the entire DOM each time.

              To create a React app, we write React components that represent different elements of the user interface. These components are organized within higher-level components that define the overall application structure. For instance, if we have a form with various elements like input fields, labels, and buttons, we can create individual React components for each element. These components are then combined into a higher-level component, such as the form component itself, which specifies the structure of the form and its contained elements.

Why Learn ReactJS?

              Today, there are many JavaScript frameworks available, such as Angular and Node.js, but React has gained significant popularity among them. Unlike traditional frameworks that rely on the Document Object Model (DOM) for data flow, React addresses some of its inefficiencies. The DOM is an object created by the browser each time a web page is loaded, dynamically updating data and creating a new DOM for the page with each modification. This repeated creation of the DOM can lead to unnecessary memory usage and reduced application performance. React, by contrast, uses a virtual DOM to optimize updates and improve performance.

    

             To address these issues, the ReactJS framework was developed. ReactJS allows you to break down your application into various components. While it still uses the traditional data flow model, it doesn’t interact directly with the browser's Document Object Model (DOM) immediately. Instead, ReactJS operates on a virtual DOM, which is an in-memory representation of the actual DOM. When changes are made to the data, they are first applied to this virtual DOM. React then calculates the necessary updates and efficiently applies only the required changes to the real DOM. This approach helps improve performance by minimizing direct interactions with the browser’s DOM. Thus, when writing a React component, you are actually creating virtual components that React will then translate into the actual DOM.