Understanding ECMAScript 6. The definitive guide for Javascript developers

355 Pages·2016·5.45 MB·English

by  Nicholas C. Zakas

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ECMAScript 6 represents the biggest update to the • How to improve asynchronous programming with
core of JavaScript in the history of the language. promises SS
In Understanding ECMAScript 6, expert developer TT
• How modules change the way you organize code
Nicholas C. Zakas provides a complete guide to the AA
object types, syntax, and other exciting changes Whether you’re a web developer or a Node.js
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that ECMAScript 6 brings to JavaScript. Every chap- developer, you’ll find Understanding ECMAScript 6
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ter is packed with example code that works in any indispensable on your journey from ECMAScript 5
JavaScript environment so you’ll be able to see new to ECMAScript 6. II
features in action. You’ll learn: NN
ABOUT THE AUTHOR
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• How ECMAScript 6 class syntax relates to more
Nicholas C. Zakas has been working on web appli-
familiar JavaScript concepts
cations since 2000, focusing on frontend develop- EE
• What makes iterators and generators useful ment, and is known for writing and speaking about CC
frontend best practices. He honed his experience
• How arrow functions differ from regular functions MM
during his five years at Yahoo!, where he was principal
• Ways to store data with sets, maps, and more frontend engineer for the Yahoo! home page. He is AA
the author of several books, including The Principles
• The power of inheritance SS
of Object-Oriented JavaScript (No Starch Press) and
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Professional JavaScript for Web Developers (Wrox).
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Understanding eCMasCript 6

U n d e r s t a n d i n g
eC Ma sC r i p t 6
the definitive guide for
Javascript developers
by Nicholas C. Zakas
San Francisco
Understanding eCMasCript 6. Copyright © 2016 by Nicholas C. Zakas.
All rights reserved. No part of this work may be reproduced or transmitted in any form or by any means,
electronic or mechanical, including photocopying, recording, or by any information storage or retrieval
system, without the prior written permission of the copyright owner and the publisher.
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ISBN-10: 1-59327-757-1
ISBN-13: 978-1-59327-757-4
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Interior Design: Octopod Studios
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Technical Reviewer: Juriy Zaytsev
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about the author
Nicholas C. Zakas has been working on web applications since 2000,
focusing on frontend development, and is known for writing and speak-
ing about frontend best practices. He honed his experience during
his five years at Yahoo!, where he was principal frontend engineer for
the Yahoo! home page. He is the author of several books, including
The Principles of Object-Oriented JavaScript (No Starch Press, 2014) and
Professional JavaScript for Web Developers (Wrox, 2012).
about the technical reviewer
Juriy Zaytsev (known online as kangax) is a frontend web developer
based in New York. He’s been exploring and writing about the quirky
nature of JavaScript since 2007. Juriy has contributed to several open
source projects, including Prototype.js and other popular projects like
his own Fabric.js. He co-founded an on-demand custom print service
called printio.ru and currently works at Facebook.

Brief Contents
Foreword by Dan Abramov . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvii
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xix
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xxi
Chapter 1: Block Bindings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
Chapter 2: Strings and Regular Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Chapter 3: Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Chapter 4: Expanded Object Functionality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Chapter 5: Destructuring for Easier Data Access . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Chapter 6: Symbols and Symbol Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .99
Chapter 7: Sets and Maps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Chapter 8: Iterators and Generators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .137
Chapter 9: Introducing JavaScript Classes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .165
Chapter 10: Improved Array Capabilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .191
Chapter 11: Promises and Asynchronous Programming . . . . . . . . . . . . . . . . . . . . . . . . . 213
Chapter 12: Proxies and the Reflection API . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .243
Chapter 13: Encapsulating Code with Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .283
Appendix A: Minor Changes in ECMAScript 6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299
Appendix B: Understanding ECMAScript 7 (2016) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311