What is React? Definition, Function & Applications

What is React?

React is an open-source JavaScript collection that is known to construct highly responsive and dynamic user interfaces. Thus, ReactJS emerges as a very effective solution for creating scalable mobile apps and front-end web with its classic component-based design. You can even build reusable UI components with React.

Jordan Walke developed React while working with Facebook as a software engineer. It was available in the public eye in 2011 on Facebook and later in 2012 on Instagram. React primarily focuses on building interactive, appealing, and natural applications. Moreover, it can provide you with the best rendering performance with just basic coding.

React allows developers to create an extensive web application that can transform data without reloading the page. You can view this in the MVC template and can be used by combining other JavaScript frameworks. Many top companies like Airbnb, Netflix, New York times, and Instagram have used React. It has also been instrumental to frameworks like Angular.js.

React has some remarkable features like server-side rendering, real-time updates, and so on. Fortunately, this JavaScript library doesn’t fail to impress anyone.

If you’re new to React framework or just refreshing your core concepts, we are here to provide you with all the fundamentals of React library. To know more, you may like to read further!

Key Features of React

React JavaScript has a huge fan base in the developers’ community for its robust features. Some of its distinguishing features are:

1. Virtual DOM

This is a core feature of React, as it facilitates flexible and fast application development. Furthermore, it enables React to replicate a web page in its virtual memory with its memory reconciliation algorithm. So, a virtual DOM is represented instead of the original DOM.

The virtual DOM re-renders the complete user interface with every modification in the application. Point to note, only the components that changed are updated, and the rest of the components remain the same in virtual representation.

Thus, React helps to make the development process cost-effective and quick for the developers.

2. JavaScript XML

JavaScript XML is popularly known as JSX. It is a syntax that is quite similar to HTML. It is primarily used to describe the appearance of an application UI. It is one of the critical features that ReactJS offers to developers. It injects components identical to HTML in the web page to create the syntax.

This helps to make writing the building blocks of ReactJS effortless. It also allows the developers to create syntax most easily.

3. One-way data binding

React offers one-way data flow, which creates one of the primary reasons for its easy work management. Unidirectional data binding is used in ReactJS, which means that the developers can not edit any component directly. However, they have to operate through the call-back function to make any changes. Hence, its process of work is called one-way data binding.

ReactJS uses Flux(a JavaScript application) to perform data control from a central point. Thus, developers can easily manage mobile applications and the web. Moreover, it enhances efficiency and makes the application more flexible.

4. React Native

React Native is customized to use native components instead of web components. In addition, it renders react-native format for ReactJS. Therefore, one should be very accurate and precise with the concepts of ReactJS to acquire the understanding and principles of React Native. These include props, state, jsx, and components.

React Native changes the react code to make it compatible with iOS and Android platforms. It also aims to provide access to native features of this platform to the developers.

5. Declarative UI

Declarative Ul is a feature that generates a simple view of the application and helps create engaging mobile applications. It enables an interactive user interface for web and mobile applications. ReactJS adequately updates just the right components with the help of this feature to have proper data modification.

This feature enables to make code more readable while also simplifying debugging.

6. Component-based Architecture

From the above features highlighted, it is clear that the architecture of ReactJS is a component-based platform. It is divided into multiple components wherein each component has its unique ability and specific logic.

Component-based architecture proclaims that React is written in JavaScript and not by using a template. So, developers can walk through the application without affecting the DOM.

Component, Props, and State

1. Components

Components are considered as the basic creating blocks of any ReactJS application. To be precise, a single application generally consists of multiple components. It is the most critical piece of the user interface. It helps to separate the UI into reusable and independent parts that can quickly be processed.

Components are classified into two main domains, which are as follows:

  • Functional Component

Functional components are simply represented by a presentational function. This function takes props and changes a React element to render it to the page. Mostly, whenever possible, it is preferred to use functional components because they are predictable and concise. Furthermore, as it is purely presentational, the output is always the same as the props.

The functional component is also referred to as stateless, presentational, and dumb. All these names are obtained from the nature that functional components take on:

  • Stateless, as they do not hold or manage state.
  • Presentational, as the all put output as UI element.
  • Functional, as they are basic functions and nothing else.

Example of functional component:

const Greeting = () => <h1>Hi, I’m a dumb component!</h1>;

  • Class Component

Class components are built by using ES6 class syntax. Additionally, they have features like the ability to contain logic, local state, and few other capabilities. These components are considered to be a container or stateful and smart:

  • Class, as they are basically divided into categories.
  • Stateful, as they can hold and manage local state.
  • Smart, as they contain logic.
  • Container, as they contain or hold numerous other components.

Class components have a large markup and are the opposite of functional components. If you use them more than required can affect the performance of the code testability and readability.

The simplest form of class component:

class Greeting extends React.Component {


     return <h1>Hi, I’m a smart component!</h1>;


2. Props

Props are enabling components of ReactJS to be dynamic and easily customizable. They are the way to provide data from one computer to the other – it is a unidirectional data flow. Components can accept and return props customized React elements based on the props received.

Props are read-only, components that must never modify the props passed to it. So, for example, the same component should be given as output and input.

3. State

The state is an integral React element which uses contain information or data about the component. Over time the state of the component can be changed; whenever it changes, it leads to the rendering of the component.

The change can happen due to the response of user action or system-generated events. These changes define the component and how it will render.

Wrapping up

React offers plenty of flexibility to developers by simplifying the development process. Thanks to React Native, you can “Learn once, write anywhere.” Thus, once you understand React’s fundamental architecture and principles, you can design fully functional web and mobile applications. The fact that React has an active support community makes it an even more attractive choice for developers – you will always find someone to navigate you through app development challenges. 

If you wish to master the nitty-gritty of React and other such trending industry tools, you should definitely check out upGrad’s Software Technology courses. upGrad promises overall development powered by peer-to-peer learning across a global learner base of 40,000+ students. Apart from a well-structured curriculum, learners enjoy interactive live sessions with top instructors and industry experts.

Is Reactjs frontend or backend?

Reactjs is an open-source front-end framework based on JavaScript. It is developed by Facebook and is best known for its virtual DOM features.

How quickly can I learn Reactjs?

You can learn the basics efficiently within six months to one year. Although it has its unique set of challenges. It is an excellent tool to work on as a web developer.

Who created Reactjs?

Reactjs was originally created by Jordan Walke. He worked at Facebook as a software engineer. His ideas were influenced by XHP and HTML components.

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