Tags: caching

Fresher service workers, by default

“Ah, this is good news!”, I thought, reading this update about how service worker scripts won’t be cached.

And that was the moment when I realised what an utter nerd I had become.

Network Information API

It looks like this is landing in Chrome. The navigator.connection.type property will allow us to progressively enhance based on connection type:

A web application that makes use of a service worker to cache resources during installation might have different bundles of assets that it might cache: a list of crucial assets that are cached unconditionally, and a bundle of larger, optional assets that are only cached ahead of time when navigator.connection.type is 'ethernet' or 'wifi'.

There are potential security issues around fingerprinting that are addressed in this document.

How much storage space is my Progressive Web App using? | Dean Hume

You can use navigator.storage.estimate() to get a (vague) idea of how much space is available on a device for your service worker caches.

It’s not working! Should I blame caching?

Finally, the answer to one of the two hard questions in computer science.

Offline Web Applications | Udacity

This is a free online video course recorded by Jake a couple of years back. It’s got a really good step-by-step introduction to service workers, delivered in Jake’s typically witty way. Some of the details are a bit out of date, and I must admit that I bailed when it got to IndexedDB, but I highly recommend giving this a go.

There’s also a free course on web accessibility I’m planning to check out.

Progressive Web Apps - ILT  |  Web  |  Google Developers

A step-by-step guide to building progressive web apps. It covers promises, service workers, fetch, and cache, but seeing as it’s from Google, it also pushes the app-shell model.

This is a handy resource but I strongly disagree with some of the advice in the section on architectures (the same bit that gets all swoonsome for app shells):

Start by forgetting everything you know about conventional web design, and instead imagine designing a native app.

Avoid overly “web-like” design.

What a horribly limiting vision for the web! After all that talk about being progressive and responsive, we’re told to pretend we’re imitating native apps on one device type.

What’s really disgusting is the way that the Chrome team are withholding the “add to home screen” prompt from anyone who dares to make progressive web apps that are actually, y’know …webby.

Retrofit Your Website as a Progressive Web App — SitePoint

Turning your existing website into a progressive web “app”—a far more appealing prospect than trying to create an entirely new app-shell architecture:

…they are an enhancement of your existing website which should take no longer than a few hours and have no negative effect on unsupported browsers.

A Little Surprise Is Waiting For You Here — Meet The Next Smashing Magazine

An open beta of Smashing Magazine’s redesign, which looks like it could be a real poster child for progressive enhancement:

We do our best to ensure that content is accessible and enhanced progressively, with performance in mind. If JavaScript isn’t available or if the network is slow, then we deliver content via static fallbacks (for example, by linking directly to Google search), as well as a service worker that persistently stores CSS, JavaScripts, SVGs, font files and other assets in its cache.

✨Implementing “Save For Offline” with Service Workers | Una Kravets Online✨

A great little script from Una that’s perfect for blogs and news sites—allowing users to explicitly save a page for offline reading.

Modernizing our Progressive Enhancement Delivery | Filament Group, Inc., Boston, MA

Scott runs through the latest improvements to the Filament Group website. There’s a lot about HTTP2, but also a dab of service workers (using a similar recipe to my site).

A Tale of Four Caches · Yoav Weiss

A cute explanation of different browser caches:

• memory cache,
• service worker cache,
• disk cache, and
• push cache.

Service Worker, what are you? - Mariko Kosaka

This is a fun—and accurate—explanation of service workers.

There’s definitely something “alien” about a service worker—it’s kind of like a virus that gets installed on the user’s device. I’ve taken to describing it as “a man-in-the-middle attack on your own website” which makes sound a bit scarier than is necessary.

The Service Worker Lifecycle  |  Web  |  Google Developers

Jake goes into the details of what exactly is happening when a service worker is installed or replaced.

This is easily the most complex part of working with service workers, and I think I’m beginning to wrap my head around it, but the good news is that, for the most part, you don’t really need to know the ins and outs of this to get started (and dev tools are now making it easier to nuke from orbit if this begins to bite).

Progressive Web Apps Simply Make Sense - Cloud Four

Progressive Web Apps versus native is the wrong question because every step on the path to a Progressive Web App makes sense on its own, irrespective of what a company does with their native apps.

Not all of your customers are going to have your app installed. For those who visit via the web, providing them with a better experience will make them happier and generate more revenue for your business.

It’s really that simple.

SpeedCurve | PWA Performance

Steve describes a script you can use on WebPageTest to simulate going offline so you can test how your progressive web app performs.

An intro to progressive web apps | 8th Light

A nice introduction to progressive web apps. There’s a little bit of confusion about permissions—whether a site has been added to the home screen or not has no effect on the permissions granted to it (for things like push notifications)—but the wrap-up nails the advantages of using the web:

No more waiting to download an app, no more prompts for updating an app. From a developer perspective, it means we will be able to iterate a lot quicker. We don’t need to wait for app store approvals anymore, and we can deploy at our own leisure.

Another advantage that a progressive web app has over a native mobile app is that it is linkable, hence it is easier to share and, probably even more importantly, can be indexed by search engines. This makes discoverability of the app a lot better.

Cross-origin Service Workers: Experimenting with Foreign Fetch | Web Updates - Google Developers

This one is definitely for service worker nerds only. I’ve been trying to get my head around this idea of “foreign fetch” which allows third parties to install service workers—could be handy for sites with APIs like Huffduffer and The Session. This article does a good job of explaining the somewhat tangled process.

lyzadanger/pragmatist-service-worker: Pragmatist’s Guide to Service Worker

Lyza put together some example code for her Smashing Conference talk on service workers. If you haven’t written a service worker before, these are really nice examples of how to grok it bit by bit.

gmetais/sw-delta: An incremental cache for the web

Here’s an interesting use of service workers: figure out the difference (the delta) between the currently-cached version of a file, and the version on the network, and then grab only the bits that have changed. It requires some configuration on the server side (to send back the diff) but it’s an interesting approach that could be worth keeping an eye on.

Adding Service Worker to a simple website - rossta.net

A nice little walkthrough of a straightforward Service Worker for a content-based site, like a blog.