Tags: browse

When I wrote about my hopes and fears for the View Transitions API, a few people latched on to this sentiment:

If the View Transitions API only works for single page apps, it could be the single worst thing to happen to the web in years.

But I also wrote:

If the View Transitions API works across page navigations, it could be the single best thing to happen to the web in years.

I think it’s worth focusing on that.

Part of the problem is that I gave my hopes and fears an equal airing. But they’re not equally likely.

Take the possibility that the View Transitions API only ships for single page apps, but never ships for regular page transitions. The consequences of that would be big—the API would act as an incentive to build single page apps. But the likelihood of that happening is small. In fact, according to Jake, there’s already an implemention for page transitions in the works at Chrome.

Now what if the View Transitions API ships for pages? The consequences would be equally big—the API would act as an incentive to ditch single page apps and build in a more performant, resilient way. Best of all, the chances of that happening are very large indeed (pretty much a certainty now, given Jake’s update).

So I made a comparison between both of the consequences, which are equally large, but I didn’t make a corresponding comparison of the likelihoods, which are not equally large. Mea culpa!

I should’ve made it clearer that, although the consequences would be really bad if the View Transitions API only supports single page apps, the actual likelihood of that is pretty slim.

That’s probably my negativity bias showing through. (The reason I have a negativity bias is because I am a human. Like, have you ever noticed that if you get feedback on something and 98% of it is positive, you inevitably fixate on the 2%?)

Anyway, the real takeaway here is that if the View Transitions API ships for pages, then the consequences will be really, really good! It would be another nail in the coffin for monolithic JavaScript frameworks slowing down the web. And best of all, the likelihood of this happening is very high!

So let me amend my closing sentences from my previous post:

If the View Transitions API only works for single page apps—which is very unlikely—it could be the single worst thing to happen to the web in years.

If the View Transitions API works across page navigations—which is very, very likely—it could be the single best thing to happen to the web in years.

The glass is half full and it’s only going to get fuller. Time to start planning for a turbo-charged web now.

If you’ve got a website with full page navigations, start thinking about how you’ll be able to apply the View Transitions API as a progressive enhancement to improve the user experience.

If you’ve got a single page app, start thinking about how to ditch a whole bunch of uneccessary dependencies to make a more lightweight foundation of HTML instead of JavaScript, and still get all those slick transitions you get in a single page app!

I am simultaneously very excited and very nervous about the View Transitions API.

You may know it by its former name—Shared Element Transitions. The name change is very recent.

I’ve been saying for years that some kind of API like this would be brilliant:

I honestly think if browsers implemented this, 80% of client-rendered Single Page Apps could be done as regular good ol’-fashioned websites.

Miriam Suzanne describes the theory of View Transitions succinctly:

Shared-element transitions are designed to work with standard web navigation across multiple page loads, as well as page transitions in ‘single-page’ apps (often called SPAs).

This all sounds brilliant. But the devil is in the implementation details. Right now, the API only works for single page apps. This is totally understandable. For purely pragmatic reasons, single page apps are a simple use case to solve for. It’s going to take a lot more work to get this API to work for multi-page apps (or as we used to call them, websites).

If we get a View Transitions API that works across page navigations, it could potentially turbo-charge the web. It will act as a disencentive to building single page apps—you’d be able to provide swish transitions without sacrificing performance or resilience at the alter of a heavy-handed JavaScript-only architecture.

But if the API only ever works for single page apps (which is the current situation), then it will act as an incentive to make any kind of website into a single page app, regardless of whether it’s actually the appropriate architecture.

That prospect has me very worried indeed.

I’m making my feelings on this known just in case any of the implementators out there are thinking, “Hey, maybe it’s fine that this API only works for single page apps—I’m sure most people would be happy with that.”

If the View Transitions API works across page navigations, it could be the single best thing to happen to the web in years.

If the View Transitions API only works for single page apps, it could be the single worst thing to happen to the web in years.

Update: Jake says:

We’re currently landing code in Chrome for the MPA version.

Very happy to hear that! It’s already in the spec, but it’s good to hear that the implementation isn’t going to lag too much.

Also, read this follow-up.

I’ve had the opportunity to gather with my peers a few times over the past couple of months.

There was dConstruct, which I hosted. That was just lovely.

Then a few weeks ago, in spite of train strikes and travel snags, I went to Bristol to give a talk at Web Dev Conf, a really nice gathering.

This past weekend I was in London for State Of The Browser, this time as neither host nor speak, but as an attendee. It was really good!

I noticed something rather lovely. There was enough cross-over in the audiences for these events that I got to see some people more than once. That’s something that used to happen all the time but became very rare over the past two years because of The Situation.

None of the organisers of these events were pretending that Covid has gone away. Each event had different processes in place to mitigate risk. I wrote about the steps I took for dConstruct. For some people, those measures might seem to go too far. For other people, they don’t go far enough. This is a challenge that every in-person event is facing and from what I’ve seen, they’re all doing their level best.

None of these events were particularly large. Attendence was maybe somewhere between 100 and 200 people at each one. I know that there’s still a risk in any kind of indoor gathering but these events feel safer than the really big tech gatherings (like the one in Berlin where I got the ’rona—that was literally tens of thousands of people).

Anyway, all three events were thoroughly enjoyable. Partly that’s because the talks were good, but also because the socialising was really, really nice—all the nicer for being in relatively safe environments.

It’s not exactly an earth-shattering observation to point out that the social side of conferences is just as valuable as the content. But now that so many of us are working remotely, I feel like that aspect of in-person events has become even more important.

Or maybe I’m just appreciating that aspect of in-person events after spending such a long time with screen-mediated interactions only.

I wrote recently about making the switch to logical properties over on The Session.

Initially I tried ripping the band-aid off and swapping out all the directional properties for logical properties. After all, support for logical properties is green across the board.

But then I got some reports of people seeing formating issues. These people were using Safari on devices that could no longer update their operating system. Because versions of Safari are tied to versions of the operating system, there was nothing they could do other than switch to using a different browser.

I’ve said it before and I’ll say it again, but as long as this situation continues, Safari is not an evergreen browser. (I also understand that problem lies with the OS architecture—it must be incredibly frustrating for the folks working on WebKit and/or Safari.)

So I needed to add fallbacks for older browsers that don’t support logical properties. Or, to put it another way, I needed to add logical properties as a progressive enhancement.

“No problem!” I thought. “The way that CSS works, I can just put the logical version right after the directional version.”

element {
  margin-left: 1em;
  margin-inline-start: 1em;
}

But that’s not true in this case. I’m not over-riding a value, I’m setting two different properties.

In a left-to-right language like English it’s true that margin-inline-start will over-ride margin-left. But in a right-to-left language, I’ve just set margin-left and margin-inline-start (which happens to be on the right).

This is a job for @supports!

element {
  margin-left: 1em;
}
@supports (margin-inline-start: 1em) {
  element {
    margin-left: unset;
    margin-inline-start: 1em;
  }
}

I’m doing two things inside the @supports block. I’m applying the logical property I’ve just tested for. I’m also undoing the previously declared directional property.

A value of unset is perfect for this:

The unset CSS keyword resets a property to its inherited value if the property naturally inherits from its parent, and to its initial value if not. In other words, it behaves like the inherit keyword in the first case, when the property is an inherited property, and like the initial keyword in the second case, when the property is a non-inherited property.

Now I’ve got three CSS features working very nicely together:

1. @supports (also known as feature queries),
2. logical properties, and
3. the unset keyword.

For anyone using an up-to-date browser, none of this will make any difference. But for anyone who can’t update their Safari browser because they can’t update their operating system, because they don’t want to throw out their perfectly functional Apple device, they’ll continue to get the older directional properties:

I discovered that my Mom’s iPad was a 1st generation iPad Air. Apple stopped supporting that device in iOS 12, which means it was stuck with whatever version of Safari last shipped with iOS 12.