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

USER-AGENT DETECTION

User-agent detection uses the browser's user-agent string to determine information about the browser being used. The user-agent string is sent as a response header for every HTTP request and is made accessible in JavaScript through navigator.userAgent. On the server side, it is a common and accepted practice to look at the user-agent string to determine the browser being used and to act accordingly. On the client side, however, user-agent detection should be assumed to be unreliable and used in scenarios when other options are infeasible.

Among the controversial aspects of the user-agent string is its long history of spoofing, when browsers try to fool servers by including erroneous or misleading information in their user-agent string. To understand this problem, it's necessary to take a look back at how the user-agent string has evolved since the Web first appeared.