What is a Progressive Web Application (PWA)

With web development an unique challenge is lack of control over the tools visitors use to view a website. There are users with older browsers and people on newer mobile devices without support for advanced Javascript or Flash plugins. Even internet connection speeds can be a major issue on content rich websites. The core aim with Progressive enhancement is to guarantee that all the users have access to content irrespective of what device they use. Some advantages are:

- Improved SEO by ensuring that search engines get all content
- Support for browsers on mobile devices, desktops and screens with larger resolutions

PWAs allow offline, push notifications and other features. However not all features are availabile on all browsers. Feature detection is important characteristic of PWAs.

Featured web applications

Click on one of our projects below to view a detailed case study

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  eBay multi-sided platform

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  Online Event Marketplace

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  A bespoke Web Application

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  Web application in a router

How does a PWA work?

All progressive web applications require a manifest which contains links to resources and a service worker (data & offline). So what does a typical PWA manifest contain?

- Logo of the web application (Visible on home screen)
- Name of the web application
- Resources usually icons, image objects
- URL to be opened up
- Configuration data of the web application
- Default orientation of the web application
- Option to display full screen
The manifest is a simple JSON file usually labelled manifest.json.

Service workers - This is a crucial part of PWAS. Service worker is a web worker that implements a programmable network proxy, it is responsile for web/HTTP requests of the main document. A service worker is able to check for internet connection. It can either deliver content from its cache when the web server is unavailable or retrieve data and serve that content later to the page. Service workers also have one important property. They like any other web workers, work separately from the main thread. This is very crucial to maintain the performance of the web application. Service workers are responsible for managing push notifications, background sync, enabling progressive web apps to provide the high performance and rich experience of native mobile apps..

PWA limitations for web development

PWAs - Progressive web applications, have this incredible power. Ability to enchance the user experience based on the features on the device. There are two kinds of limitations to PWAs. Firstly, some vendors like Apple for iOS do not give PWAs access to all the device APIs. They want to see developers use the native application approach instead of working with open web APIs. They have also lagged behind Google for example. Secondly, not all device features work well at the moment as a PWA.

About Webdigi & Services

We are a web development company in London. We specialise in developing bespoke web applications & unique web platforms. Over the years we have helped clients build great web applications. From time to time we publish open source tools, projects and articles like this to raise awareness and contribute back to the open source community that we rely on so much!