Book Image

Learn React with TypeScript 3

By : Carl Rippon
Book Image

Learn React with TypeScript 3

By: Carl Rippon

Overview of this book

React today is one of the most preferred choices for frontend development. Using React with TypeScript enhances development experience and offers a powerful combination to develop high performing web apps. In this book, you’ll learn how to create well structured and reusable react components that are easy to read and maintain by leveraging modern web development techniques. We will start with learning core TypeScript programming concepts before moving on to building reusable React components. You'll learn how to ensure all your components are type-safe by leveraging TypeScript's capabilities, including the latest on Project references, Tuples in rest parameters, and much more. You'll then be introduced to core features of React such as React Router, managing state with Redux and applying logic in lifecycle methods. Further on, you'll discover the latest features of React such as hooks and suspense which will enable you to create powerful function-based components. You'll get to grips with GraphQL web API using Apollo client to make your app more interactive. Finally, you'll learn how to write robust unit tests for React components using Jest. By the end of the book, you'll be well versed with all you need to develop fully featured web apps with React and TypeScript.
Table of Contents (14 chapters)

Getting code coverage

Code coverage is how we refer to how much of our app code is covered by unit tests. As we write our unit tests, we'll have a fair idea of what code is covered and what code is not covered, but as the app grows and time passes, we'll lose track of this.

Jest comes with a great code coverage tool, so we don't have to keep what is covered in our heads. In this section, we'll use this to discover the code coverage in the project we worked on in the previous section, where we mocked axios:

  1. Our first task is to add an npm script that will run the tests with the coverage tracking tool switched on. Let's add a new script called test-coverage that includes the --coverage option when react-scripts is executed:
"scripts": {
"start": "react-scripts start",
"build": "react-scripts build",