Learning Progressive Web Apps

Use Service Workers to Turbocharge Your Web Apps “You have made an excellent decision in picking up this book. If I was just starting on my learning path to mastery of Progressive Web Apps, there are not many folks I would trust more to get me there than John.” —Simon MacDonald, Developer Advocate, Adobe Software developers have two options for the apps they build: native apps targeting a specific device or web apps that run on any device. Building native apps is challenging, especially when your app targets multiple system types—i.e., desktop computers, smartphones, televisions—because user experience varies dramatically across devices. Service Workers—a relatively new technology—make it easier for web apps to bridge the gap between native and web capabilities. In Learning Progressive Web Apps, author John M. Wargo demonstrates how to use Service Workers to enhance the capabilities of a web app to create Progressive Web Apps (PWA). He focuses on the technologies that enable PWAs and how to use those technologies to enhance your web apps to deliver a more native-like experience. Build web apps a user can easily install on their local system and that work offline or on low-quality networks Utilize caching strategies that give you control over which app resources are cached and when Deliver background processing in a web application Implement push notifications that enable an app to easily engage with users or trigger action from a remote server Throughout the book, Wargo introduces each core concept and illustrates the implementation of each capability through several complete, operational examples. You’ll start with simple web apps, then incrementally expand and extend them with state-of-the-art features. All example source code is available on GitHub, and additional resources are available on the author’s companion site, learningpwa.com. Register your book for convenient access to downloads, updates, and/or corrections as they become available. See inside book for details.

Table of Contents:
Foreword xi Preface xii Acknowledgments xv About the Author xvi Chapter 1: Introducing Progressive Web Apps 1 First, a Little Bit of History 2 PWAs Are . . . 2 Making a Progressive Web App 4 PWA Market Impact 6 PWAs and App Stores 7 Wrap-Up 7 Chapter 2: Web App Manifest Files 9 Save to Home Screen 11 Making a Web App Installable 16 Anatomy of a Web App Manifest 17 Controlling the Installation Experience 26 Preparing to Code 27 App Installation in Action 29 Troubleshooting 41 Manifest Generation and More 42 Wrap-Up 42 Chapter 3: Service Workers 43 PWA News 43 Introducing Service Workers 44 Preparing to Code 46 Registering a Service Worker 52 Service Worker Scope 60 The Service Worker Lifecycle 60 Wrap-Up 66 Chapter 4: Resource Caching 67 Service Worker Cache Interface 67 Preparing to Code 69 Caching Application Resources 70 Implementing Additional Caching Strategies 91 Wrap-Up 98 Chapter 5: Going the Rest of the Way Offline with Background Sync 99 Introducing Background Sync 100 Offline Data Sync 103 Choosing a Sync Database 105 Preparing to Code 110 Enhancing the PWA News Application 111 Wrap-Up 128 Chapter 6: Push Notifications 129 Introducing Push Notifications 129 Remote Notification Architecture 132 Preparing to Code 134 Generating Encryption Keys 134 Validating Notification Support 138 Checking Notification Permission 138 Getting Permission for Notifications 139 Local Notifications 142 Notification Options 144 Subscribing to Notifications 148 Unsubscribing from Notifications 154 Remote Notifications 156 Dealing with Subscription Expiration 162 Sending Notifications to Push Services 162 Wrap-Up 164 Chapter 7: Passing Data between Service Workers and Web Applications 165 Preparing to Code 166 Send Data from a Web App to a Service Worker 167 Send Data from a Service Worker to a Web App 169 Two-Way Communication Using MessageChannel 171 Wrap-Up 180 Chapter 8: Assessment, Automation, and Deployment 181 Assessing PWA Quality Using Lighthouse 181 Preparing to Code 182 PWABuilder 190 PWAs and the Microsoft Store 202 Wrap-Up 205 Chapter 9: Automating Service Workers with Google Workbox 207 Introducing Workbox 207 Generating a Precaching Service Worker 208 Add Precaching to an Existing Service Worker 215 Controlling Cache Strategies 218 Wrap-Up 224 Index 225

About the Author :
John M. Wargo is a product manager, software developer, writer, presenter, father, husband, and geek. He spent more than 30 years working as a professional software developer, first as a hobbyist, then in enterprise software, and finally, for the last 15 years, in mobile development. He is the author of six books on mobile development and was a long-time contributor to the open-source Apache Cordova project. By day, he’s a principal program manager on the App + Cloud Experiences team at Microsoft. His website is johnwargo.com.