Part 1. Defining Progressive Web Apps

In 2015, the International Telecommunication Union estimated that about 3.2 billion people, or almost half of the world’s population, would be online by the end of that year. Think about that number for a second. 3.2 billion people. That’s about 32,000 football stadiums full of people! It almost seems too big to comprehend. As these people come online they will be doing so on different devices with different connection speeds and ever-changing conditions. As web developers, trying to cater to all these different scenarios seems daunting to say the least. This is where Progressive Web Apps (PWAs) come in. They provide us as developers with the ability to build faster, more resilient, and more engaging websites that can be accessed by billions around the world. The chapters in this first part of the book dive straight into defining exactly what PWAs are and what they can do.

In chapter 1, you’ll learn about the benefits of PWAs. We’ll look at businesses that are already harnessing the power of PWAs to improve their users’ browsing experience. We’ll also dissect a real-world PWA and look at how companies such as Twitter and Flipkart have built their own PWAs. A key component of PWAs is the Service Worker, and I’ll be covering this topic in depth, as well as the lifecycle that Service Workers go through when loaded in a web browser.