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Progressive Web Application Development by Example

You're reading from   Progressive Web Application Development by Example Develop fast, reliable, and engaging user experiences for the web

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Product type Paperback
Published in Jul 2018
Publisher Packt
ISBN-13 9781787125421
Length 354 pages
Edition 1st Edition
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Author (1):
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Chris Love Chris Love
Author Profile Icon Chris Love
Chris Love
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Table of Contents (12) Chapters Close

Preface 1. Introduction to Progressive Web Apps 2. Creating a Home Screen Experience with a Web Manifest FREE CHAPTER 3. Making Your Website Secure 4. Service Workers – Notification, Synchronization, and Our Podcast App 5. The Service Worker Life Cycle 6. Mastering the Cache API - Managing Web Assets in a Podcast Application 7. Service Worker Caching Patterns 8. Applying Advanced Service Worker Cache Strategies 9. Optimizing for Performance 10. Service Worker Tools 11. Other Books You May Enjoy

Lazy loading images

Images can delay your overall page load experience due to image numbers and their size. There are different strategies for optimizing image delivery. The first one you should consider is lazy loading images below the fold.

This could be a very tricky technique to execute. Modern APIs can help you, the IntersectionObserver (https://developer.mozilla.org/en-US/docs/Web/API/Intersection_Observer_API) API in particular gives you the ability to detect when elements are entering the viewport. You can designate the distance and time estimated threshold for an element to appear.

The IntersectionObserver API will trigger an event to let you know when an element is about to be displayed. At this point, you can initiate an image download if necessary. This means that your pages images will not be loaded in the initial render process, but be loaded as needed. This can...

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