dom VS IntersectionObserver

in plain htmx, you can target an area that doesn't disrupt a playing video (e.g. the comments box appending to the comments) or you can use a morphing algorithm that disrupts the DOM less.

i have my own morphing algorithm (and a corresponding htmx plugin that allows you to use it) called idiomorph:

https://github.com/bigskysoftware/idiomorph/

i've also been working with the chrome team to get a feature added they are calling "atomic moves":

https://github.com/whatwg/dom/issues/1255

this would allow us to move elements around in the DOM without losing things like play state or focus or whatever

very excited for this last idea, I think it will be a huge boon for the web in general, not just for htmx

What I said in my previous comment is observably true. Try making a demo where it isn't.

> A DOM node is a living mutable thing, but the JavaScript object representing that node is not.

The JavaScript object is mutable. The first example in the article shows this.

> That is also why a node list is not an array.

Modern APIs on the web return platform arrays (eg JavaScript arrays). https://webidl.spec.whatwg.org/#js-sequence - here's where the WebIDL spec specifies how to convert a sequence to a JavaScript array.

I'm fully aware of NodeList. There's a reason the spec calls them "old-style" https://dom.spec.whatwg.org/#old-style-collections

> I can understand how this is confusing if you have never operated without a framework, but otherwise it’s really straightforward

Sighhhhhh. I've been a web developer for over 20 years, and spent a decade on the Chrome team working on web platform features. Most of my career has been on the low-level parts of the platform.

Could it be possible that people are disagreeing with you, not because they're stupid, but because you're in the wrong? Please try to be open minded. Try creating some demos that test your opinions.

Domenic Denicola (the man who ruined promises) probably will as well.

https://github.com/whatwg/dom/issues/67

I'm pretty sure it is, since I get "TypeError: nodes[i].parentNode.href is undefined" and "TypeError: $mainmenu.parent(...).get(...) is undefined" errors on both Pale Moon and LibreWolf. Which is part of Shadow/DOM, and originated from google (https://hacks.mozilla.org/2015/06/the-state-of-web-components/). Not sure when this particular thing was introduced, since it's a "living standard"/experimental feature (https://dom.spec.whatwg.org/).

JSX chose to align names to the DOM spec [0]. Same for htmlFor and friends.

[0] https://dom.spec.whatwg.org/#ref-for-dom-element-classname%E...

You can see why I say this here: https://dom.spec.whatwg.org

The product logos in this article's cover image include different languages and technologies some of which are still relevant for web development today: HTML, CSS, JavaScript / ES / TypeScript (and the DOM), SVG, PDF, PHP, SQL (mySQL, MariaDB), mongoDB, Node.js (the most successful server-side implementation of JavaScript so far).

Thanks for the shout-out! I think I mention this in the talk, but note that YMMV. I designed that benchmark as a kind of "worst-case scenario" where shadow DOM / scoped styles really show a benefit. Depending on your CSS rules, DOM size, and amount of thrashing, the perf benefit could be small to large.

Also, it's still possible to shoot yourself in the foot, especially if you have a large/complex stylesheet repeated across multiple shadow roots. (Not because of the repetition – that's optimized in browsers [1] – but rather because of the number of DOM nodes affected.)

That said, I still think the perf benefits of shadow DOM have been undersung. And Declarative Shadow DOM makes it way more useful.

[1]: https://github.com/whatwg/dom/issues/831#issuecomment-585489...

We luh-luh-luv you! They gestated and nurtured the spec. They fought over bike sheds! All for us!!

You should only create the images (or set the src) for the images which are visible to the user. See our infinite scroll example for a naive implementation. More elaborated code might use the https://www.w3.org/TR/intersection-observer/.

I got a little curious on the statuses of these standards and went on a bit of searching.

> CSS contain (CSS Containment Module Level 2) - First published in 2019, still Editor's Draft[1]. Not supported by Safari/WebKit.

> CSS offset-path (Motion Path Module Level 1) - First published in 2015, still Editor's Draft[2]. Not supported by Safari/WebKit.

> CSS overflow-anchor (CSS Scroll Anchoring Module Level 1) - First published in 2020, still Editor's Draft[3]. Not supported by Safari/WebKit.

> Resolution media queries (dppx) - W3C Recommendation since 2012[4]. Not supported by Safari/WebKit.

> :focus-visible (Selectors Level 4) - First published in 2011, still Editor's Draft[5]. Not supported by Safari/WebKit.

- Touch Events - W3C Recommendation since 2013[6]. Supported on iOS 3.2 (2010). I assume the author meant Pointer Events[7] which became W3C recommendation since 2019, and supported on 13.2 (2019).

> BroadcastChannel - WHATWG Living Standard[8]. Blocked by privacy concern on WebKit side since 2020[9]. Initial support landed in WebKit trunk as of 2021-07.[10]

> beforeprint/afterprint - WHATWG Living Standard[11]. Supported by Safari/WebKit since 2019 (iOS 13).

> Regex Lookbehind - ECMAScript 2018[12]. Not supported by Safari/WebKit.

> scrollIntoView (CSSOM View Module) - First introduced in CSSOM View Module since 2011, still Editor's Draft[13]. Not supported by Safari/WebKit.

> Screen Orientation API - First committed in wc3/screen-orientation in 2012, still a W3C Working Draft[14]. Not supported by Safari/WebKit.

> Date and time input types - WHATWG Living Standard[15], partial support by Safari/WebKit since 2012 (iOS 5) but no week/min/max.

> Service Workers - W3C Candidate Recommendation since 2019[16]. Supported by Safari/WebKit since 2018 (iOS 14.5).

- AbortSignal - WHATWG Living Standard[17]. Supported by Safari/WebKit since 2018 (iOS 11.3)

- Intersection Observer - First published in 2017, still W3C Working Draft[18]. Supported by Safari/WebKit since 2019 (iOS 12.2).

- Client-side form validation - WHATWG Living Standard[19]. Supported by Safari/WebKit since 2017 (iOS 10.3).

[1]: https://drafts.csswg.org/css-contain/#contain-property

[2]: https://drafts.fxtf.org/motion/#offset-path-property

[3]: https://drafts.csswg.org/css-scroll-anchoring/#exclusion-api

[4]: https://www.w3.org/TR/css3-mediaqueries/#resolution

[5]: https://drafts.csswg.org/selectors-4/#the-focus-visible-pseu...

[6]: https://www.w3.org/TR/touch-events/

[7]: https://www.w3.org/TR/pointerevents/

[8]: https://html.spec.whatwg.org/multipage/web-messaging.html#br...

[9]: https://github.com/whatwg/html/issues/5803

[10]: https://bugs.webkit.org/show_bug.cgi?id=227924

[11]: https://html.spec.whatwg.org/multipage/timers-and-user-promp...

[12]: https://262.ecma-international.org/9.0/

[13]: https://drafts.csswg.org/cssom-view/#dom-element-scrollintov...

[14]: https://www.w3.org/TR/screen-orientation/

[15]: https://html.spec.whatwg.org/multipage/input.html#date-state...

[16]: https://www.w3.org/TR/service-workers/

[17]: https://dom.spec.whatwg.org/#abortsignal

[18]: https://www.w3.org/TR/intersection-observer/

[19]: https://html.spec.whatwg.org/multipage/forms.html#client-sid...

W3.Org

I've used https://github.com/w3c/IntersectionObserver/tree/main/polyfill in the past and it's pretty much just import and forget.

// app/javascript/controllers/infinite_scoll_controller.js import { Controller } from "stimulus" export default class extends Controller { static targets = ["scrollArea", "pagination"] connect() { this.createObserver() } createObserver() { const observer = new IntersectionObserver( entries => this.handleIntersect(entries), { // https://github.com/w3c/IntersectionObserver/issues/124#issuecomment-476026505 threshold: [0, 1.0], } ) observer.observe(this.scrollAreaTarget) } handleIntersect(entries) { entries.forEach(entry => { if (entry.isIntersecting) { this.loadMore() } }) } loadMore() { const next = this.paginationTarget.querySelector("[rel=next]") if (!next) { return } const href = next.href fetch(href, { headers: { Accept: "text/vnd.turbo-stream.html", }, }) .then(r => r.text()) .then(html => Turbo.renderStreamMessage(html)) .then(_ => history.replaceState(history.state, "", href)) } }

import { Controller } from "stimulus" export default class extends Controller { static targets = ["entry"] static values = { path: String, } connect() { this.createObserver(); } createObserver() { let observer; let options = { // https://github.com/w3c/IntersectionObserver/issues/124#issuecomment-476026505 threshold: [0, 1.0] }; observer = new IntersectionObserver(entries => this.handleIntersect(entries), options); observer.observe(this.entryTarget); } handleIntersect(entries) { entries.forEach(entry => { if (entry.isIntersecting) { // https://github.com/turbolinks/turbolinks/issues/219#issuecomment-376973429 history.replaceState(history.state, "", this.pathValue); } }); } }