wpt VS WHATWG HTML Standard

To reply mostly with my WPT Core Team hat off, mostly summarising the history of how we've ended up here:

A build script used by significant swaths of the test suite is almost certainly out; it turns out people like being able to edit the tests they're actually running. (We _do_ have some build scripts — but they're mostly just mechanically generating lots of similar tests.

A lot of the goal of WPT (and the HTML Test Suite, which it effectively grew out of) has been to have a test suite that browsers are actually running in CI: historically, most standards test suites haven't been particularly amenable to automation (often a lot of, or exclusively, manual tests, little concern for flakiness, etc.), and with a lot of policy choices that effectively made browser vendors choose to write tests for themselves and not add new tests to the shared test suite: if you make it notably harder to write tests for the shared test suite, most engineers at a given vendor are simply going to not bother.

As such, there's a lot of hesitancy towards anything that regresses the developer experience for browser engineers (and realistically, browser engineers, by virtue of sheer number, are the ones who are writing the most tests for web technologies).

That said, there are probably ways we could make things better: a decent number of tests for things like Grid use check-layout-th.js (e.g., https://github.com/web-platform-tests/wpt/blob/f763dd7d7b7ed...).

One could definitely imagine a world in which these are a test type of their own, and the test logic (in check-layout-th.js) can be rewritten in a custom test harness to do the same comparisons in an implementation without any JS support.

The other challenge for things like Taffy only targeting flexbox and grid is we're unlikely to add any easy way to distinguish tests which are testing interactions with other layout features (`position: absolute` comes to mind!).

My suggestion would probably be to start with an issue at https://github.com/web-platform-tests/rfcs/issues, describing the rough constraints, and potentially with one or two possible solutions.

It also helps that there are tests

https://web-platform-tests.org/

You can see how Mozilla tests the compliance of their built-in elements in the Gecko repository (the ok and is assertions are defined in their SimpleTest testing framework). And here's the Web Platform Tests' reflection harness, with data for each built-in element in sibling files, that almost every browser pass.

We have our own test suite (orginally derived from the test suite of Meta's Yoga layout library [0]) which consists of text fixtures that are small HTML snippets [1] and a test harness [2] that turns those into runnable tests, utilising headless chrome both to parse the HTML and to generate the assertions based on the layout that Chrome renders (so we are effectively comparing our implementation against Chrome). We currently have 686 generated tests (covering both Flexbox and CSS Grid).

We would like to utilise the Web Platform Test suite [3], however these are not in a standard format and many of the tests require JavaScript so we are not currently able to do that.

[0]: https://github.com/facebook/yoga

[1]: https://github.com/DioxusLabs/taffy/tree/main/test_fixtures

[2]: https://github.com/DioxusLabs/taffy/tree/main/scripts/gentes...

[3]: https://github.com/web-platform-tests/wpt/tree/master/css/cs...

The metrics are based on the passing rate for the web-platform-tests (WPT) project, the automated test suite for web standards. The completion rate is categorised as either stable, or experimental. There is no definition of what experimental entails, presumably features that are behind experimental flags are included. Stable is better to go off in any case.

Depends on what you are trying to achieve. You can run WPT MSE https://github.com/web-platform-tests/wpt/tree/master/media-source and WebCodecs https://github.com/web-platform-tests/wpt/tree/master/webcodecs tests manually to learn by doing.

Manually running the tests in Web Platform Tests should keep you busy.

Not sure what you mean? I referred to Web API's, which generally means Web platform API's; that is Web platform API's tested by Web Platform Tests https://github.com/web-platform-tests/wpt.

If you want CSS to be the same across browsers then help implement CSS tests and file bugs

https://www.w3.org/Style/CSS/Test/Overview.en.html

https://web-platform-tests.org/

better specs are great, but tests will actually find the edge cases and lead to more convergence.

Run all these tests locally https://github.com/web-platform-tests/wpt/tree/master/dom.

WHAT-WG HTML

There's a long-standing WHATWG feature request open for it here: https://github.com/whatwg/html/issues/2791

And several userland custom element implementation, like https://www.npmjs.com/package//html-include-element

One of the cool things that you can do with client-side includes and shadow DOM is render the included HTML into a shadow root that has s, so that the child content of the include element is slotted into a shell implemented by the included HTML.

This lets you do things like have the main page be the pre-page content and the included HTML be a heavily cached site-wide shell, and then another per-user include with personalized HTML - all cached appropriately.

The `allow` attribute on iframes is a relatively recent API addition from 2017

https://github.com/whatwg/html/pull/3287

I think there's a pretty strong argument at this point for this kind of replacing DOM with a response behavior being part of the platform.

I think the first step would be an element that lets you load external content into the page declaratively. There's a spec issue open for this: https://github.com/whatwg/html/issues/2791

And my custom element implementation of the idea: https://www.npmjs.com/package/html-include-element

Then HTML could support these elements being targets of links.

> Consider https://www.ietf.org/rfc/rfc1866.txt vs https://html.spec.whatwg.org/multipage/

I thought, oh, that's not so bad. Then I realized what I was looking at was a 10 page index.

I'd love to see something like HTMX get standardized, but I'm extremely pessimistic for HTMX's prospects for standardization in HTML.

In talking to a few standards folks about it, they've all said, "oh, yeah, you want declarative AJAX; people have tried and failed to get that standardized for years." Even just trying to get

to target a section of the page that isn't an has been argued about and hashed out for years.<p>Why is that? Well, for example, here's the form you have to fill out to start standardizing a front-end feature. <a href="https://github.com/whatwg/html/issues/new?assignees=&labels=addition%2Fproposal%2Cneeds+implementer+interest&projects=&template=1-new-feature.yml">https://github.com/whatwg/html/issues/new?assignees=&labels=...</a><p>It asks three main questions:<p>* What problem are you trying to solve?

The issue with a single global event handler is discussed here: https://github.com/WICG/close-watcher#a-single-event

If you use popover="", you get the kind of functionality you're discussing for free. For

, the discussion is in progress and reaching a conclusion: https://github.com/whatwg/html/issues/9373