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How To Learn ReactJS 2021: A Complete Guide For Beginners

Shailendra Chauhan  Print   26 min read  
03 Sep 2021
 
Intermediate
287 Views

Web developers and front-end developers sometimes find it frustrating to write the same code at various places. For instance, if they require adding a button on multiple pages, they need to write a lot of code. Those developers using other frameworks suffer from the challenges to revise most codes even while crafting components that are modified frequently. A library or framework is required so that they can break the complex components as well as reuse the codes to faster accomplish their projects. For this problem, ReactJS is the solution. For those willing to pursue Reactjs Certification, the knowledge of the fundamentals of ReactJS helps a lot.

Let’s first know what exactly ReactJS is and how it is useful:

ReactJS Tutorial - javatpoint

What is ReactJS?

ReactJS is a well-known open-source JavaScript library which is developed by Facebook. For both the web as well as mobile-based applications, it can manage the view layer. The fundamental use of ReactJS is to build reusable UI components.  It boasts a user-friendly interface. Its powerful community assists you always.

The key feature of ReactJS is to develop a User Interface (UI) for improving application speed. Moreover, the JavaScript virtual DOM is faster than the standard DOM and it is responsible for improving the performance. 

One of the exciting aspects of ReactJS is it is based on components. So, the complex code is broken down into components that assist the developers to better organize their codes. The entire UI categorizes into reusable components. All those components are made separately and ultimately embedded into a parent component which is rendered later on.  Each component is accountable for generating a tiny, reusable portion of HTML code.  These components can be nested with other ones for building complex applications with some simple building blocks. 

The data patterns and React’s components improve readability and assist you to deal with large applications. ReactJS can be used on client-side, server-side, and many other frameworks. 

After you have a fundamental understanding of React, you can begin building some basic projects like a simple todo-app, a simple calculator app, building a shopping cart, displaying GitHub’s user statistics through GitHub API.

 

To know how to Learn Reactjs Step By Step, you must know the pre-requisites as mentioned below:

Pre-requisites to learn ReactJS:

  • Fundamental knowledge of HTML, CSS, and JavaScript

  • Certain ES6 features of Javascript including Let and Const, Arrow Functions, Class, and ‘this’ keyword

  • Fundamentals of NodeJS & Code Editors

1. HTML, CSS, JavaScript:

Amazingly Useful HTML, CSS and JavaScript Tools and Libraries | by Bradley Nice | Level Up! | Medium

For an experienced developer, this section is not needed. But for beginners, it is vital to know HTML, CSS, and Javascript. These three are the fundamental foundations of frontend web development. All of them work collectively to develop a fully functional website or web app. These 3 basic concepts should be covered in the React Learning path.

2. Javascript’s ES6 features:

ES6 is recognized as the version of JavaScript and multiple features are included. To begin learning ReactJS, you must have knowledge of Let and Const, Arrow Functions, Class and ‘this’ keyword. Let’s explore each of these ES6 features:

i. Let and Const

Instead of the ‘var’ keyword, you would use ‘let’ and ‘const’. Both of them are different than var. Let defines a local variable that limits its scope to a particular block in which declaration is done. Const defines a constant variable and the corresponding values cannot be modified.

ii. Arrow Function: 

It enables you to write shorter syntax for functions. With this function, your code becomes cleaner and more readable. 

iii. Class and ‘this’ Keyword: 

It is necessary to learn the Object-Oriented Programming concepts such as Method, Class, and Objects in ES6. It is possible that you already learn these concepts in Java or C++.

The ‘this’ keyword depicts the current object in execution. For many developers, ‘this’ keyword concept seems confusing. So, make sure to clear any confusion around it. Also, you need to learn to Apply, Call and Bind methods. These methods are used to bind or connect ‘this keyword’ to a particular object.

3. NodeJS Fundamentals & Code Editors:

To work on ReactJS, it is important to understand NodeJS fundamentals. When you go through the React tutorial, these basic concepts are covered. NodeJS represents an execution environment for Javascript. Many people assume that it is a programming language but it is false. Each browser contains a JavaScript Engine that is incorporated inside browsers. For instance, Mozilla Firefox contains SpiderMonkey and Chrome contains a V8 engine.

It is not allowed to carry out any operation outside of the browser. You cannot perform operations like OS operations, File operations, and Network Operations. This is where the NodeJS Fundamentals prove to be useful. Node enables you to accomplish such operations exterior to the browser. Moreover, it is embedded with Chrome’s V8 engine.

NPM (Node Package Manager) is a package manager useful for installing node modules as well as packages into your project. The installation is identical to PIP for python.

Import and Export keywords:

After you install the Node module through NPM inside your project, you need to use the ‘import’ keyword for using that module.

Use the ‘Export’ keyword while creating a component/module. You just need to return a part instead of all variables and methods.

React Router: 

Dynamic transitions with react-router and react-transition-group

React routing let you comprehend how routing functions in a React application. To learn ReactJS, you need to learn how to load the content of a precise page or how to effectively redirect to a precise page through React Router.

After you have enough understanding of React Router, it becomes easy to create projects like the Hacker News clone or a simple CRUD application. When you prepare for React Interview Questions and Answers, questions may be asked on the React Router.

Webpack: 

In Javascript, Webpack is a module bundler that assists developers to uphold dependencies like the static files for your project. Hence, the burden on the shoulders of developers reduces. Webpack too comes with loaders that execute explicit tasks for your project.

Server Rendering: 

When you learn this concept, you can create components within the server and then render that in form of HTML within your browser. After every JavaScript module gets downloaded inside the browser, the ReactJS comes into play. Server rendering is one of the exciting features of React and it could be used with any back-end technologies.

Redux:

You need to control states across components in a complex application. Redux is a Javascript library that resolves this issue. It maintains the application states. In Redux, all your states are stored in a single source.

Read, Also

  1. Everything you need to know about create react app
  2. React vs React native: Key features,Pros & Cons 
  3. Functional component react you should know
  4. Things you need to know about react navigation
  5. Top 5 React developer tools for software development
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