Book Image

React Key Concepts

By : Maximilian Schwarzmüller
Book Image

React Key Concepts

By: Maximilian Schwarzmüller

Overview of this book

As the most popular JavaScript library for building modern, interactive user interfaces, React is an in-demand framework that’ll bring real value to your career or next project. But like any technology, learning React can be tricky, and finding the right teacher can make things a whole lot easier. Maximilian Schwarzmüller is a bestselling instructor who has helped over two million students worldwide learn how to code, and his latest React video course (React — The Complete Guide) has over six hundred thousand students on Udemy. Max has written this quick-start reference to help you get to grips with the world of React programming. Simple explanations, relevant examples, and a clear, concise approach make this fast-paced guide the ideal resource for busy developers. This book distills the core concepts of React and draws together its key features with neat summaries, thus perfectly complementing other in-depth teaching resources. So, whether you've just finished Max’s React video course and are looking for a handy reference tool, or you've been using a variety of other learning materials and now need a single study guide to bring everything together, this is the ideal companion to support you through your next React projects. Plus, it's fully up to date for React 18, so you can be sure you’re ready to go with the latest version.
Table of Contents (16 chapters)

4. Working with Events & State

Activity 4.1: Building a Simple Calculator

In this activity, you'll build a very basic calculator that allows users to add, subtract, multiply, and divide two numbers with each other.

Perform the following steps to complete this activity:

  1. Add four new components into an src/components folder in a new React project: Add.js, Subtract.js, Divide.js, and Multiply.js (also add appropriately named component functions inside the component files).
  2. Add the following code to Add.js:
    function Add() {
      function changeFirstNumberHandler(event) {
      function changeSecondNumberHandler(event) {
      return (
          <input type="number" onChange={changeFirstNumberHandler} /> + 
          <input type="number" onChange={changeSecondNumberHandler} /> = ...
    export default Add;

This component outputs a paragraph that contains two input elements (for the two numbers...