Link tags: cache

It’s Time to Build a Progressive Web App. Here’s How – The New Stack

Much as I appreciate the optimism of this evaluation, I don’t hold out much hope that people’s expectations are going to change any time soon:

Indeed, when given a choice, users will opt for the [native] app version of a platform because it’s been considered the gold standard for reliability. With progressive web apps (PWAs), that assumption is about to change.

Nonetheless, this is a level-headed look at what a progressive web app is, mercifully free of hand-waving:

• App is served through HTTPS.
• App has a web app manifest with at least one icon. (We’ll talk more about the manifest shortly.)
• App has a registered service worker with a fetch event handler. (More on this later too.)

Service Workers | Go Make Things

Chris Ferdinandi blogs every day about the power of vanilla JavaScript. For over a week now, his daily posts have been about service workers. The cumulative result is this excellent collection of resources.

Adding Response Metadata to Cache API Explainer by Aaron Gustafson and Jungkee Song

This is a great proposal that would make the Cache API even more powerful by adding metadata to cached items, like when it was cached, how big it is, and how many times it’s been retrieved.

Request with Intent: Caching Strategies in the Age of PWAs – A List Apart

Aaron outlines some sensible strategies for serving up images, including using the Cache API from your service worker script.

Offline Page Descriptions | Erik Runyon

Here’s a nice example of showing pages offline. It’s subtly different from what I’m doing on my own site, which goes to show that there’s no one-size-fits-all recipe when it comes to offline strategies.

Blog service workers and the chicken and the egg

This is a great little technique from Remy: when a service worker is being installed, you make sure that the page(s) the user is first visiting get added to a cache.

Offline listings

This is brilliant technique by Remy!

If you’ve got a custom offline page that lists previously-visited pages (like I do on my site), you don’t have to choose between localStorage or IndexedDB—you can read the metadata straight from the HTML of the cached pages instead!

This seems forehead-smackingly obvious in hindsight. I’m totally stealing this.

Distinguishing cached vs. network HTML requests in a Service Worker | Trys Mudford

Less than 24 hours after I put the call out for a solution to this gnarly service worker challenge, Trys has come up with a solution.

Cache-Control for Civilians – CSS Wizardry

Harry breaks down cache-control headers into steps that even I can understand. I’ll be using this a reference for sure.

Going Offline First (Video Series)

A five-part video series from Ire on how she built the “save for offline” functionality on her site.

The first one is about getting a set set up on Ghost so you can probably safely skip that one and go straight to the second video to get down to the nitty-gritty of the Cache API and service workers.

Inlining or Caching? Both Please! | Filament Group, Inc., Boston, MA

This just blew my mind! A fiendishly clever pattern that allows you to inline resources (like critical CSS) and cache that same content for later retrieval by a service worker.

Crazy clever!

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.

How Fast Is Amp Really? - TimKadlec.com

An excellent, thorough, even-handed analysis of AMP’s performance from Tim. The AMP format doesn’t make that much of a difference, the AMP cache does speed things up (as would any CDN), but it’s the pre-rendering that really delivers the performance boost …as long as you give up your URLs.

But right now, the incentives being placed on AMP content seem to be accomplishing exactly what you would think: they’re incentivizing AMP, not performance.

Reliable Experiences - PWA Roadshow - YouTube

A good hands-on introduction to service workers from Mariko.

Welcoming Progressive Web Apps to Microsoft Edge and Windows 10 - Microsoft Edge Dev BlogMicrosoft Edge Dev Blog

It’s really great to hear about how Microsoft will be promoting progressive web apps as first-class citizens …but it’s really unhelpful that they’re using this fudgy definition:

Progressive Web Apps are just great web sites that can behave like native apps—or, perhaps, Progressive Web Apps are just great apps, powered by Web technologies and delivered with Web infrastructure.

Although they also give a more technical definition:

Technologically speaking, PWAs are web apps, progressively enhanced with modern web technologies (Service Worker, Fetch networking, Cache API, Push notifications, Web App Manifest) to provide a more app-like experience.

Nice try, slipping notifications in there like that, but no. No, no, no. Let’s not fool ourselves into thinking that one of the most annoying “features” of native apps is even desirable on the web.

If you want to use notifications, fine. But they are absolutely not a requirement for a progressive web app.

(A responsive design, on the other hand, totally is.)

Workers at Your Service | WebKit

Here’s an interesting insight on how WebKit is going to handle the cleanup of unused service workers and caches:

Service worker and Cache API stored information will grow as a user is browsing content. To keep only the stored information that is useful to the user, WebKit will remove unused service worker registrations after a period of a few weeks. Caches that do not get opened after a few weeks will also be removed.

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.

AMP: breaking news | Andrew Betts

A wide-ranging post from Andrew on the downsides of Google’s AMP solution.

I don’t agree with all the issues he has with the format itself (in my opinion, the fact that AMP pages can’t have script elements is a feature, not a bug), but I wholeheartedly concur with his concerns about the AMP cache:

It recklessly devalues the URL

Spot on! And as Andrew points out, in this age of fake news, devaluing the URL is a recipe for disaster.

It’s hard to avoid the idea that the primary objective of AMP is really about hosting publisher content inside the Google ecosystem (as is more obviously the objective of Facebook Instant Articles and Apple News).