Book Image

Professional JavaScript

By : Hugo Di Francesco, Siyuan Gao, Vinicius Isola, Philip Kirkbride
Book Image

Professional JavaScript

By: Hugo Di Francesco, Siyuan Gao, Vinicius Isola, Philip Kirkbride

Overview of this book

In depth knowledge of JavaScript makes it easier to learn a variety of other frameworks, including React, Angular, and related tools and libraries. This book is designed to help you cover the core JavaScript concepts you need to build modern applications. You'll start by learning how to represent an HTML document in the Document Object Model (DOM). Then, you'll combine your knowledge of the DOM and Node.js to create a web scraper for practical situations. As you read through further lessons, you'll create a Node.js-based RESTful API using the Express library for Node.js. You'll also understand how modular designs can be used for better reusability and collaboration with multiple developers on a single project. Later lessons will guide you through building unit tests, which ensure that the core functionality of your program is not affected over time. The book will also demonstrate how constructors, async/await, and events can load your applications quickly and efficiently. Finally, you'll gain useful insights into functional programming concepts such as immutability, pure functions, and higher-order functions. By the end of this book, you'll have the skills you need to tackle any real-world JavaScript development problem using a modern JavaScript approach, both for the client and server sides.
Table of Contents (12 chapters)


In 2018, Google released the Puppeteer JavaScript library, which has drastically increased the ease with which end-to-end testing can be set up on a JavaScript-based project. Puppeteer is a headless version of the Chrome web browser, meaning that it has no GUI component. This is crucial, as it means we're testing our applications with a full Chrome browser, rather than a simulation.

Puppeteer can be controlled through jQuery-like syntax, where elements on an HTML page are selected by ID or class and interacted with. For example, the following code opens Google News, finds a .rdp59b class, clicks on it, waits 3 seconds, and finally takes a screenshot:

(async() => {
  const browser = await puppeteer.launch();
  const page = await browser.newPage();
  await page.goto('');
  const more = await page.$(".rdp59b");;
  await page.waitFor(3000);
  await page.screenshot({path: 'news.png'});
  await browser...