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

ASYNCHRONOUS ITERATION

Asynchronous execution and the iterator protocol are two extremely pervasive themes in new ECMAScript features over recent releases. Asynchronous execution involves releasing control of the execution thread to allow slow operations to finish before regaining control, and the iterator protocol involves defining a canonical ordering for arbitrary objects. Asynchronous iteration is merely the logical assimilation of these two concepts.

A synchronous iterator provides you with a { value, done } pair each time next() is invoked. Of course, this requires that the computation and resource fetching needed to determine the contents of this pair be completed by the time the next() invocation exits—otherwise, these values are indeterminate. When using a synchronous iterator to iterate over values that are determined asynchronously, the main execution thread will be blocked while waiting for the asynchronous operation to complete.

With asynchronous iterators, this problem...