Getting started with progressive web apps (PWAs) can be an exciting venture for developers and businesses alike. In this article, we'll delve into the world of PWAs, exploring their benefits, features, and best practices for creating a seamless user experience.

What is a Progressive Web App?

At its core, a PWA is a type of web application that combines the best aspects of the web and native apps. It's an app that works everywhere, but is supercharged in modern browsers. This enhanced experience can be achieved through progressive enhancement, which involves layering additional features on top of your existing content.

Think of it like building a peanut M&M: the peanut represents your content, the chocolate coating is your presentation layer, and the hard candy shell is where many PWA features live. These experiences can include fast loading times, push notifications, and the ability to install the app on a user's home screen.

The Power of PWAs

PWAs are designed to provide an exceptional user experience, regardless of the device or browser used. They offer:

  • Progressive: Works for every user, regardless of browser choice
  • Responsive: Fits any form factor, from desktop to mobile
  • Connectivity-independent: Enhanced with service workers to work offline or on low-quality networks
  • App-like: Uses the app shell model to provide app-style navigation and interactions
  • Fresh: Always up-to-date thanks to the service worker update process
  • Safe: Served via TLS to prevent snooping and ensure content hasn't been tampered with
  • Discoverable: Identifiable as "applications" thanks to W3C manifests and service worker registration scope, allowing search engines to find them
  • Re-engageable: Makes re-engagement easy through features like push notifications
  • Installable: Allows users to "keep" apps they find most useful on their home screen without the hassle of an app store
  • Linkable: Easily share via URL and not require complex installation

Getting Started with PWAs

If you're new to PWAs, don't worry – we've got you covered. Here are some key principles to get started:

Web App Manifest

The manifest enables your web app to have a more native-like presence on the user's home screen. It allows the app to be launched in full-screen mode (without a URL bar being present), provides control over the screen orientation, and supports defining a Splash Screen and theme color for the address bar.

You can find sample manifest files in Web Starter Kit and Google Chrome samples. Additionally, there are tools like Manifest Generator and Web Manifest validator available to help you create your own manifests.

"Add to Home Screen" Banner

Chrome on Android has supported adding sites to the home screen for a while now, but recent versions also support proactively suggesting sites be added using native Web App install banners.

To display the app install prompts, your site must:

  • Have a valid web app manifest
  • Be served over HTTPS (see Let's Encrypt for a free certificate)
  • Have a valid service worker registered
  • Be visited twice, with at least 5 minutes between visits

Service Worker for Offline Caching

A service worker is a script that runs in the background, separate from your web page. It responds to events, including network requests made from pages it serves. A service worker has an intentionally short lifetime and can be used to provide users with an offline experience.

Service workers are powerful for offline caching but also offer significant performance wins in the form of instant loading for repeat visits to your site or web app. You can cache your application shell so it works offline and populate its content using JavaScript.

By mastering the principles of progressive web apps, you'll be well on your way to creating fast, secure, and engaging web applications that provide an exceptional user experience.