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How To Code in React.js
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By Joe Morgan
Developer and author at DigitalOcean.
How To Code in React.js


React is a popular JavaScript framework for creating front-end applications, such as user interfaces that allow users to interact with programs. Originally created by Facebook, it has gained popularity by allowing developers to create fast applications using an intuitive programming paradigm that ties JavaScript with an HTML-like syntax known as JSX.

In this series, you will build out examples of React projects to gain an understanding of this framework, giving you the knowledge you need to pursue front-end web development or start out on your way to full stack development.

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Starting a new JavaScript project with React used to be a complicated process. But now, Create React App includes all the JavaScript packages you need to run a React project, including code transpiling, basic linting, testing, and build systems. In this tutorial, you’ll use Create React App to start a React application. You’ll also run a build to create a minified version of your app, use a server with hot reloading to give you instant feedback, and explore the React file structure.

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How To Create React Elements with JSX

Updated on March 11, 2024

JSX is an abstraction that allows you to write HTML-like syntax in your JavaScript code and will enable you to build React components that look like standard HTML markup. Since you are also writing JavaScript, you’ll be able to take advantage of JavaScript functions and methods, including array mapping and short-circuit evaluation for conditionals. In this tutorial, you’ll build a working application that uses a variety of JSX features to display elements that have a built-in click listener.

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How To Create Custom Components in React

Published on April 16, 2020

Custom components are independent pieces of functionality that you can reuse in your code, and are the building blocks of all applications built on the React framework. Often, they can be simple JavaScript functions and classes, but you use them as if they were customized HTML elements. Buttons, menus, and any other front-end page content can all be created as components. In this tutorial, you’ll build your own custom component, and use this distinction to organize your project’s file structure.

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Props are arguments that you provide to a JSX element in a React application. They look like standard HTML props, but they aren’t predefined and can have many different JavaScript data types, including numbers, strings, functions, arrays, and even other React components. In this tutorial, you’ll create custom components by passing props to your component. After adding props, you will use PropTypes to define the type of data you expect a component to receive.

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In this tutorial, you’ll create wrapper components with props using the React JavaScript library. Wrapper components are components that provide a default structure to display the child components. This pattern is useful for creating user interface (UI) elements that are used repeatedly throughout a design, like modals, template pages, and information tiles. You’ll use the rest and spread operators to collect unused props to pass down to nested components.

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How To Style React Components

Published on June 9, 2020

In this tutorial, you’ll learn three different ways to style React components: plain Cascading Style Sheets (CSS), inline styles with JavaScript-style objects, and JSS, a library for creating CSS with JavaScript. To illustrate these methods, you’ll build an example Alert component that will either show a success style or an error style depending on the prop. You will then refactor it using each of the styling options to see the similarities and differences between each.

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In React, state refers to a structure that keeps track of how data changes over time in your application. Managing state is a crucial skill in React because it allows you to make interactive web applications. In this tutorial, you’ll run through an example of managing state on class-based components. This tutorial will first show you how to set state using a static value and then how to set a state as the current state, using a product page component as an example.

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React Hooks are a broad set of tools in the React front-end JavaScript library that run custom functions when a component’s props change. Since this method of state management doesn’t require you to use classes, developers can use Hooks to write shorter, more readable code that is easy to share and maintain. Throughout this tutorial, you’ll learn how to set state using the useState and useReducer Hooks, using a product page component with a shopping cart as an example.

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In this tutorial, you’ll share state across multiple components using React context. React context is an interface for sharing information with other components without explicitly passing the data as props. This means that you can share information between a parent component and a deeply nested child component, or store site-wide data in a single place and access them anywhere in the application. To illustrate this, this tutorial will create a website where users can build custom salads.

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The React Developer Tools browser extension gives you an interface for exploring the React component tree of your JavaScript app, along with the current props, state, and context for individual components. It can also show you which components are re-rendering and can generate graphs to show how long individual components take to render. In this tutorial, you will install React Developer Tools on the Google Chrome, then use it to analyze the performance of a sample app that analyzes text.

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In JavaScript apps using the React front-end library, you can use event handlers to update state data, trigger prop changes, or prevent default browser actions. To do this, React uses a SyntheticEvent wrapper instead of the native Event interface. In this tutorial, you’ll build several sample components that handle user events. You’ll learn how to add event handlers to components, pull information from the SyntheticEvent, and add and remove Window event listeners.

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How To Build Forms in React

Published on September 23, 2020

Since most React applications are single page applications (SPAs), web forms usually do not submit the information directly from the form to a server. Instead, they capture the form information on the client-side and send or display it using additional JavaScript code. In this tutorial, you’ll build forms using React Hooks and state objects. By the end of this tutorial, you’ll be able to make a variety of forms using text inputs, checkboxes, select lists, and more.

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In JavaScript development with the React library, asynchronous programming presents unique problems. When you use React functional components for example, asynchronous functions can create infinite loops. In this tutorial, you’ll find out how to avoid asynchronous programming bugs, load data with the useEffect React Hook, and split your code for on-demand lazy loading using React lazy and Suspense.

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In this tutorial, you’ll use the useEffect and useState React Hooks to fetch and display information in a sample application, using JSON server as a local API for testing purposes. You’ll load information when a component first mounts and save customer inputs with an API. You’ll also refresh data when a user makes a change and learn how to ignore API requests when a component unmounts.

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How To Manage State in React with Redux

Published on October 20, 2020

Redux is a popular data store for JavaScript and React applications. In this tutorial, you’ll use store, actions, reducers, and the useSelector Hook to build a bird watching test application. You’ll then pull data into your components and dispatch new changes to update the data.

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In React, routers help create and navigate between the different URLs that make up your web application. React Router is designed with intuitive components to let you build a declarative routing system for your application. In this tutorial, you’ll install and configure React Router, build a set of routes, and connect to them using the <Link> component. You’ll also use React Hooks to access data and other routing information and create nested routes.

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In your React application, you can use authentication to manage which users have access to which pages. In this tutorial, you’ll create a React application using a token-based authentication system. You’ll create a mock API that will return a user token, build a login page that will fetch the token, and check for authentication without rerouting a user. As you build the application, you’ll explore different methods for storing tokens, including using localStorage and sessionStorage.

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In React applications, performance problems often originate from component re-rendering. Because of this, learning how to prevent unneeded re-renders can help to optimize the performance of your React app. In this tutorial, you’ll look at how different actions can trigger re-renders and how you can use Hooks and memoization to minimize expensive data calculations. By the end of this tutorial, you’ll be familiar with many performance enhancing Hooks, such as the useMemo and useCallback Hook.

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This tutorial covers steps to deploy a React application with Nginx service on an Ubuntu machine.

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DigitalOcean’s App Platform is a Platform as a Service (PaaS) product that lets you configure and deploy applications from a source repository. This can be a quick and efficient way to deploy your React applications, and if you are using React to build a site with no backend, you can use App Platform’s free tier. In this tutorial, you will create a React app with Create React App, push it to GitHub, then deploy it to App Platform for a quick continuous deployment option.

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How To Code in React.js eBook

Published on July 30, 2021

This book is an introduction to React that works from the foundations upward. Each chapter takes you a little deeper into the React ecosystem, building on your previous knowledge. Along the way, you’ll learn how to maintain internal state, pass information between parts of an application, and explore different options for styling your application.

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