declarative-shadow-dom VS WHATWG HTML Standard

Take a look at Declarative Shadow DOM: https://github.com/mfreed7/declarative-shadow-dom

Hmm, I see that Chromium shipped their implementation a year ago now; I had missed that. Other than that, there’s been no real change in the situation in the last almost two years (since Shoelace 2.0 was released, the last time I examined the situation). And there still doesn’t look to be any real interest in actually implementing it outside of Google: Mozilla are unenthusiastic though not against it <https://mozilla.github.io/standards-positions/#declarative-s...>, and WebKit still find fault with some aspects of the design (https://lists.webkit.org/pipermail/webkit-dev/2021-February/..., https://github.com/mfreed7/declarative-shadow-dom/issues/9), though they’re content most of the earlier issues are ironed out.

So you certainly can’t rely on scriptless server-side rendering of Shadow DOM being possible—it’ll work in Chromium only, and it’ll probably be at least another year or two before other browsers even contemplate doing anything with it.

(And of course, even once Shadow DOM is serialisable, that’s a far shot from a particular frameworky thing being SSR-compatible, but I was quibbling over the Shadow DOM and impossibility aspects, so I shan’t step back on that.)

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