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)

Chapter 2: What is New in TypeScript 3

  1. We have the following function that draws a point:
function drawPoint(x: number, y: number, z: number) {
...
}

We also have the following point variable:

const point: [number, number, number] = [100, 200, 300];

How can we call the drawPoint function in a terse manner?

drawPoint(...point);
  1. We need to create another version of the drawPoint function that can call by passing the x, y, and z point values as parameters:
drawPoint(1, 2, 3);

Internally in the implementation of drawPoint we draw the point from a tuple data type, [number, number, number]. How can we define the method parameter(s) with the required tuple?

function drawPoint(...point: [number, number, number]) {
...
}
  1. In your implementation of drawPoint, how can you make the z point optional?
function drawPoint(...point: [number, number, number?]) {
...
}
  1. We have a function called...