You're reading from Professional JavaScript for Web Developers Discover an easy-to-learn guide to upgrade your JavaScript skills

Product type Paperback

Published in Nov 2019

Publisher Wiley

ISBN-13 9781119366447

Length 1144 pages

Edition 4th Edition

Languages

JavaScript

Tools

Combine

Concepts

Web Programming

Author (1):

Matt Frisbie

View More author details

Table of Contents (37) Chapters

COVER FREE CHAPTER

FOREWORD

INTRODUCTION

1 What Is JavaScript?

2 JavaScript in HTML

3 Language Basics

4 Variables, Scope, and Memory

5 Basic Reference Types

6 Collection Reference Types

7 Iterators and Generators

8 Objects, Classes, and Object-Oriented Programming

9 Proxies and Reflect

10 Functions

11 Promises and Async Functions

12 The Browser Object Model

13 Client Detection

14 The Document Object Model

15 DOM Extensions

16 DOM Levels 2 and 3

17 Events

18 Animation and Graphics with Canvas

19 Scripting Forms

20 JavaScript APIs

21 Error Handling and Debugging

22 XML in JavaScript

23 JSON

24 Network Requests and Remote Resources

25 Client-Side Storage

26 Modules

27 Workers

28 Best Practices

A ES2018 and ES2019

B Strict Mode

C JavaScript Libraries and Frameworks

D JavaScript Tools

INDEX

END USER LICENSE AGREEMENT

PAGE VISIBILITY API

A major pain point for web developers is knowing when users are actually interacting with the page. If a page is minimized or hidden behind another tab, it may not make sense to continue functionality such as polling the server for updates or performing animations. The Page Visibility API aims to give developers information about whether or not the page is visible to the user.

The API itself is very simple, consisting of three parts:

document.visibilityState—A value indicating one of four states:
- The page is in a background tab or the browser is minimized.
- The page is in the foreground tab.
- The actual page is hidden, but a preview of the page is visible (such as in Windows 7 when moving the mouse over an icon in the taskbar shows a preview).
- The page is being prerendered off-screen.
visibilitychange event—This event fires when a document changes from hidden to visible, or vice versa.
document.hidden—A Boolean value indicating if the page is hidden...