Book Image

Progressive Web Application Development by Example

By : Chris Love
Book Image

Progressive Web Application Development by Example

By: Chris Love

Overview of this book

Are you a developer that wants to create truly cross-platform user experiences with a minimal footprint, free of store restrictions and features customers want? Then you need to get to grips with Progressive Web Applications (PWAs), a perfect amalgamation of web and mobile applications with a blazing-fast response time. Progressive Web Application Development by Example helps you explore concepts of the PWA development by enabling you to develop three projects, starting with a 2048 game. In this game, you will review parts of a web manifest file and understand how a browser uses properties to define the home screen experience. You will then move on to learning how to develop and use a podcast client and be introduced to service workers. The application will demonstrate how service workers are registered and updated. In addition to this, you will review a caching API so that you have a firm understanding of how to use the cache within a service worker, and you'll discover core caching strategies and how to code them within a service worker. Finally, you will study how to build a tickets application, wherein you’ll apply advanced service worker techniques, such as cache invalidation. Also, you'll learn about tools you can use to validate your applications and scaffold them for quality and consistency. By the end of the book, you will have walked through browser developer tools, node modules, and online tools for creating high-quality PWAs.
Table of Contents (12 chapters)

The cost of CSS and JavaScript

The real culprit behind delaying page load time is the overuse of CSS and JavaScript. Both are rendering blocking, which means that when they are being processed, nothing else happens.

Remember from the chapters on service workers, the browser uses a single thread to manage all the rendering tasks, including processing CSS and JavaScript. While this thread is doing that processing, no rendering can take place.

Developers are often naïve about the impact CSS and JavaScript has on their pages loading. Often, this comes down to forgetting what devices real users load web pages with, that is, mobile phones.

Developers generally work on high end workstations and laptops. They also load their work on those devices while developing. Therefore, they perceive their pages as loading instantly.

The discrepancy is a combination of no network latency, high...