- Custom HTML-like syntax
<button @click="" .disabled="" />
// valid JS, invalid lit
const tagName= "a";
`<${tagName} href="">Some link</${tagName}>`
// classMap looks like a regular JS function, but it's not.
// Both of these will produce an error
<div class="my-widget ${classMap(dynamicClasses)} ${classMap(dynamicClasses)}">Static and dynamic</div>
<div data-class="${classMap(dynamicClasses)}">Static and dynamic</div>
- Experimental compiler: https://github.com/lit/lit/tree/main/packages/labs/compiler#...
Yes, Lit templates give some special meaning to attribute names with a few prefixes. No, it's not "HTML-like". It's valid HTML. Not that it matters much. You bring this up all the time but I'm not sure what the actual criticism is. Developers seem to understand the small syntax carve-out just fine.
No, there are no custom JavaScript rules. Templates have some rules. I'm not sure why they wouldn't? In general you can't make things like tag and attribute names dynamic because you can't change them in HTML. You can actually write the template you show with what we call static templates though.
`classMap()` is a template directive. It has some rules about how it's used in templates, just like other JS functions can have rules about how their used. I'm not sure what makes that not a function.
But to your main point: Lit is not like React because it's not a framework. Lit helps you make custom elements - it's an implementation detail of some web components. Everything else about those elements: how you instantiate them, style them, where they work, etc., is all defined by the HTML and DOM standards. React is a framework, and defines its own rules about how its components work.
I love that I get to choose how everything works. I have custom systems for routing, styling, signals, API interactions. I control who gets passed what and when. It makes the app feel light, responsive, and -- most importantly, it fits in my head and I understand how it's put together because I chose it, not because I learned it from someone.
Yes, yes I do. Because Web Components are almost 15 years now, and they still struggle with the most basic of things. How's that abandoned roadmap going? https://w3c.github.io/webcomponents-cg/2022.html
> No, there are no custom JavaScript rules. Templates have some rules.
That is "here are regular JS functions. However, you cannot use them as regular JS functions in these specific contexts". Reminds me of certain very specific rules about specific functions in specific contexts in some other framework. Can't put my finger on it.
> I'm not sure what makes that not a function.
I never said it doesn't make it a function.
> But to your main point: Lit is not like React because it's not a framework.
Yeah, React wasn't a framework either, but just a library. Everything about DOM elements that React produces, how you instantiate them, style them, where they work etc. is all defined by the HTML and DOM standards.
But then React grew in the number of features, and can no longer be called a library even though still the only thing it does is output some DOM nodes.
I guess you'll insist on Lit being "just a library" even after it adds a ton of other functionality all other frameworks already have or are moving towards.
> I'm not sure what the actual criticism is
The criticism is usual: Lit is rapidly absorbing all the features from all the other frameworks and becoming a framework itself while many of its developers and proponents can't stop shitting all over other frameworks.
Typescript has JSX built in so when "I made my own framework" I just used that.
Looking at the first example:
First I had to switch it from TS to JS. As I don't consider something that needs compilation before it runs to be lightweight.
Then, the first line is:
import {html, css, LitElement} from 'lit';
And when I use the "download" button on the playground version of the first example, I get a "package.json" which defines dependencies. That is also certainly not something a browser can handle.
So do I assume correctly that I need to set up a webserver, a dependency manager, and a serverside runtime to use these "light weight" components?
Or am I missing something? What would be the minimal amount of steps to save the example and actually have it run in the browser?
https://unpkg.com/lit@3.3.1/index.js?module
You can even dynamically import that in the a running browser console and use it directly on any webpage.
I guess for most people the standard is to install things from NPM
replace 'lit' with something like this:
https://unpkg.com/lit@3.3.1/index.js?module
That isn't a criticism of projects that don't use npm, and it doesn't make them less valid, but it makes sense for the documentation to match the average developer's experience.
Overall, the example does not seem like something that is supposed to run directly in the browser without some kind of intermediate step.
That is why I asked what the minimal number of steps would be to download the example and have it work locally.
If I understand correctly, your criticism is that the people for whom Web Components is a good fit are publicly discussing the reasons why they prefer it over other solutions?
The main problem is that for a "niche technology" it sure infects too many standards, requires an insane amount of new standards and makes supporting things needlessly complicated.
A few links here: https://news.ycombinator.com/item?id=45114450
There are some good parts in the ~30 standards they require, but instead of just the good parts you get the whole horse, and the cart it's attached to, and the cargo in the cart.
> your criticism is that the people for whom Web Components is a good fit are publicly discussing the reasons why they prefer it over other solutions?
It's not.
I do wonder, why are you on this crusade? Are you afraid that people are at some point gonna be persuaded by Lit / Web Components, and that you need to be there to prevent that from happening?
It all looked nice in theory, but one thing shadow DOM makes worse is A11y, because element ids are now scoped and all the missing describe-by, label-for for things that should link to other side of the fence are a massive pain in the ass.
Big part of it is just skill issue on our part of course.
I am currently working on a web components framework, and I scrapped everything halfway through after I realized that you very rarely want that much encapsulation. Now, you can turn it on if you really need it, and I even made a way where you can pass references to DOM elements and stylesheets and such into each component so you can pierce the shadow veil easily. I have one demo to show it off, but I'm really having trouble imagining when someone would actually want to use it. The only time I can imagine it being useful would be building component libraries inside of large organizations.
I'm not ready to show off my framework yet, but I'm very certain that this leads to a better DX.
The trick is that the components really do need to be self contained, and you need to use slots and custom attributes to bridge the gaps. Styling is the most annoying part for me, but I just include the same global imports that the main page has.
Does this actually happen a lot? Allowing for the fact that people would rarely admit to it just being about resume padding, I feel like just wanting to _use_ the thing is a far more common motivation for poorly rationalised technology choices.
https://github.com/gitaarik/lit-state
I've used it extensively myself, for creating complex web apps with many (nested) components interacting with each other.
I don't understand why Lit hasn't gained more popularity, because for me it is basically React, but then more browser-native, much less boiler plate, and much faster rendering. There are some things you have to get used to, but when you do it doesn't limit you in any way.
I made this alternative implementation of lit-html to use as a research bed a long time ago when I was actively contributing to lit: https://github.com/ruphin/lite-html
Judging from this thread, many people have their own implementations, which is great to hear. I think there's a lot of value in solutions that are so simple that anyone can reproduce them.
Not sure why Lit showed up on the front page tonight :)
The project is Converse.js, an XMPP chat client. It's an old project that was originally created back in 2013 with Backbone.js.
I first replaced all templates with `lit-html` when I first heard about that, and then when lit-element (and now "lit") came out, I started rewriting the project to use that.
This app has since been integrated into many different websites that rely on other frameworks like React and the fact that Converse.js is a web component (<converse-root />) makes this easier.
If you're interested, here's the Github repo: https://github.com/conversejs/converse.js And you can demo it here: https://chat.conversejs.org/
You'll need an XMPP account (see https://providers.xmpp.net/ for possible providers).
Part of using web components, for me, is that it is just javascript. There is no upgrades or deprecations to think about. Of course those things still exist on the server though, but it is easier to maintain it there.
Native web component APIs don't have the DX that many people expect though, because they are so low-level. Lit provides just that declarative reactivity on top.
In simple scenarios like just dropping it in an html page, codepen, or something like that I really enjoyed it though.
I have actually wrote a few web components by hand in an environment where I didn't want any external dependencies and when that requirement was dropped I really liked how easy was to convert them to LitElement (and how much nicer it is to work with them).
I also have embraced the shadow DOM which is a default, but I think it's more trouble than it's worth. Now I use LitElement without shadow DOM and it works great as well.
In comparison, Angular is a monster, and React is designed for the old browser capabilities, and is now staying around by inertia, not by inherent quality.
Its .html temples were shipped unmodified directly to the client (yes, including comments). Except they weren't actually html, and sometimes the browser would try to clean them up, breaking the template.
Reactivity was achieved through all kinds of weird mechanisms (eg monkey-patching arrays to watch for mutations). It would frequently resort to polling on every tick or break completely.
DI used TypeScripts experimental decorators, even long after it was clear that it would never become stable.
On the other hand, templates weren't type checked.
Its .html temples were shipped unmodified directly to the client. Except they weren't actually html, and sometimes the browser would try to clean them up, breaking the template.
Reactivity was achieved through all kinds of weird mechanisms (eg monkey-patching arrays to watch for mutations). It would frequently resort to polling on every tick or break completely.
DI used TypeScripts experimental decorators, even long after it was clear that it would never become stable.
On the other hand, templates weren't type checked.
I think lit should distance itself from that mess if possible
What would be the benefit of rebuilding these components in Lit over using Vue to build them?
https://vuejs.org/guide/extras/web-components#building-custo...
As I recall inside Google it was maybe one in a thousand elements that needed any changes at all. I updated the entire internal codebase of many tens of thousands of elements in a couple weeks of part time work.
But more importantly Lit 2 and Lit 3 are interoperable, so there's not the same pressure to update. When an element or library updates from Lit 2 to Lit 3, it can do that as a point release, because its public API is the same. This really reduces the amount of upgrade toil you have to deal with.
Really love the abstraction that makes web components easy to use.
I shipped a project with Lit and I liked it, but I didn't like that I'd need to know the complete project scope up front that I could write everything from the ground up. I know I could use React component for some of the harder stuff but at that point might as well use React and avoid bundling two systems
- https://github.com/vaadin/web-components
- https://github.com/material-components/material-web (very, very sadly killed by google management)
I love it when I visit one of my pages and use Lighthouse to check it out and have nearly straight across 100 scores. Also, I usually have really great performance on phones as well because the pages are so light and quick to render.
Typescript can even add Intellisense to "customElements.get" by augmenting CustomElementRegistry: https://gist.github.com/cecilemuller/72fbb3bc3a77d82c8a969cd...
My editor: https://needcoolershoes.com
If you're curious about lit and like longer form content - I recommend watching the [0] http 203 video that talks about lit element and other tools like it
Using other frameworks to set up web view’s just don’t feel the same by comparison. I just want nested web components, and I just want Lit to help me define them. Tagged template literals for constructing HTML feels so much better than suffering through JSX.
I use it in almost all my personal websites. And when I don't use it, I end up reinventing half of it and realize I should have used it from the start. This command is in most of my projects:
curl -L https://cdn.jsdelivr.net/npm/lit-html@3/lit-html.js -o ${project}/lit-html.js
Another thing I like from Lit is that with the CDN bundle, it's straightforward to experiment and use all the features without needing a build step.
Yes, Lit uses shadow DOM by default (for good reasons, I think!) and yes you can turn it off component-by-component, but that does bring some challenges.
Shadow DOM is most fundamentally just a private branch of the DOM tree for a component's internal DOM details.
Frameworks have this implicitly with DOM defined in a component's template vs passed as children. But that distinction isn't visible to other code, the browser, and CSS. This is both good and bad.
The biggest thing this separate tree gives us is the ability to tell what nodes are "children" - those are the light DOM children. Once you can separate children from internals, you can build slots. Slots are holes in the internals that children get rendered into.
Without something like shadow DOM you can't have slots. And without slots you don't have interoperable composition and you don't have viable container elements. You need some way to place children in an element that isn't confused with the element's own DOM.
So to me, before encapsulation and style scoping, interoperable composition is the most important feature, and that's really why Lit defaults to shadow DOM on. Without it we'd need some special `.children` property and Lit's component composition suddenly wouldn't be compatible with everyone else.
But the style encapsulation is often a major pain for developers, especially if they're trying to integrate web components into an existing system with whole-page stylesheets. It's a big blocker to a lot of design systems porting to web components.
That's one reason I proposed something called "Open Styleable Shadow Roots"[1] which would let styles from outer scopes cascade into a shadow root - a way to break open style encapsulation but keep slots. It's been hard convincing browser vendors that this is needed, but I'm holding out hope that it makes progress soon.
I'm sold and build all my work and personal apps with it and have for many years. I wrote this article about why in 2022:
Getting Started with Web Components & Lit
https://medium.com/gitconnected/getting-started-with-web-com...
Sometimes, I am wondering why it is not more widely used ...
Web components are nice because they're browser-native, but they don't support reactivity, which in hindisight, is a massive oversight, issue, whatever you want to call it - it's hindered adoption.
Lit is nice because there's a very straightforward progression from web components.
There is a proposal in TC39 for native signals, which I think would make a huge dent towards library-less reactivity.
I'm also working on a proposal for native reactive templating which would more-or-less obsolete lit-html. I wrote about the idea some on my blog:
- The time is right for a DOM templating API https://justinfagnani.com/2025/06/26/the-time-is-right-for-a...
- What should a native DOM templating API look like? https://justinfagnani.com/2025/06/30/what-should-a-dom-templ...
Apps are well served because they have more control about how components are used: they can import the same shared styles into every component, take are to not double-register elements, etc.
But I think there are some important standards still missing that would open things up even more in the design system and standalone components side:
- Scoped custom element registries. This moves away from a single global namespace of tag names. Seems like it's about to ship in Safari. Chrome next.
- Open styleable shadow roots. Would allow page styles to flow into shadow roots. This would make building components for use with existing stylesheets easier.
- CSS Modules. Import CSS into JS. Shipping in Chrome. About to land in Firefox.
- ARIA reference target: make idref-based reference work across shadow roots
Or with opinions like this: https://dev.to/ryansolid/web-components-are-not-the-future-4...
O if you want to go down the technical rabbit hole, you can search for all the issues people have with them, e.g.: https://x.com/Rich_Harris/status/1841467510194843982
The good part of react and friends is it's just javascript and the class is imported and referenced normally, not with a weak string-binding-through-registry kind of way.
Now add types to the mix and shadow dom and it brings constant problems without any upside.
https://news.ycombinator.com/item?id=45107388
I assume someone else looked it up and liked it enough to submit it.
Can I reassign name in the example by using document.querySelector?
I can't find clear information about how re-rendering and stateful third-party components interact.
Let's say I have a stateful data table web component that I use in the template. Is it going to be re-created every time the template is re-rendered (loosing its internal state)?
Elements are kept stable as long as the template containing them is rendered.
The template docs try to get this across by saying that Lit "re-render only the parts of template that have changed." Maybe that needs more detail.
There are details here: https://github.com/lit/lit/blob/main/dev-docs/design/how-lit...
HTTP/3, import maps, and HTML preloads can make unbundled app deployment almost reasonable in some cases. You'd still miss out on minification and better compression form a bundle. Shared compression dictionaries will make this better though.
* Built-in state management especially as in v3 (ref/reactive) is super powerful, and you can test the setup function logic by itself without any dependency on DOM which is convenient. By comparison, reactivity in Lit is basic (by design), and mostly work on the widget level -- if something changes, you need to trigger the update process of the widget.
* The lifecycle is also a bit simpler. In Lit, you often need to work with lifecycle callbacks like firstUpdated, connected, shouldUpdate, updated, disconnected etc. (You don't need to implement these for simpler widgets, but often you have to.) You can easily run into bugs if you are not careful, especially in the less common situation where your widget can be both temporarily and permanently removed from the DOM, in which case you need to make sure the state of the widget is properly perserved, which isn't a thing you need to worry about in Vue. We got bitten by this multiple times.
Unless there is a strong technical reason, I suggest that you focus on shipping features instead of changing your tech stack. Rebuilding your widgets is a very time consuming task with, well, near 0 impact on the user.
Vue is more of a "framework" solution and has more things built-in. You can do the same things with Lit, but the implementation would look different, because you'd lean more on native APIs. A good example of that is the event model, Vue has some event model built in, but with Lit you would use EventTarget.dispatchEvent().
Lit is a runtime solution, it doesn't require a build and you can load your source directly in the browser. Vue on the other hand requires some form of compiler stage to produce something your browser can use. Compilers these days are fast, and Lit is specifically engineered to not have runtime performance overhead, so in practice this difference is rather minor. It is a very fundamental difference, so I think it's worth pointing out.
Vue can compile to other targets. If you are only delivering Web Components, this is mostly irrelevant, but in theory a consumer might be able to use the Vue components directly in their Vue project, which might give them a better DX. On the other hand, Lit is specifically designed to produce Web Components, so you'll probably have a bit less friction compares to using Vue, e.g when some Vue concept doesn't compile cleanly to Web Components.
Is there a major benefit to choosing one implementation over the other? I don't think so, unless you have a very particular requirement that one of them addresses that the other doesn't. For nearly all cases, it is just a different implementation syntax.
In most cases the only relevant metric in deciding between them is what technology your developers are more familiar/comfortable with.
Make a fat bundle with a web component or even a mount() function exported and run whatever fits your devx inside, with the API surface as narrow as possible. As long as it's self contained and the size is reasonable, nobody on a consumer side cares how you cook, so optimize your own pipelines to build, test and publish it.
People will build adapters to fit it into their stuff anyway and will let you know.
We use them to make fields reactive mostly, and I love how declarative they are. But we use them sparingly. I personally don't love how some libraries try to put a lot of things into decorators that could have been standard class features, like a static field or a method.
edit: As mentioned by skrebbel, decorators are optional. Every decorator has a simple plain-JS way of doing it. Event reactive properties: https://lit.dev/docs/components/properties/#declaring-proper...
We also put a lot of effort into making all of our documentation and playground samples on lit.dev available in both JavaScript and TypeScript with decorators. There's a switch that will change everything on the site from JS to TS globally.
I can think about few other ways, such as using higher order functions/classes, using getOwnPropertyDescriptor or doing stuff at construction.
> As mentioned by skrebbel, decorators are optional
This is not a pro, it's a con. The more ways there are to achieve the same result the more inconsistent projects become IRL.
Also, do you really want to metaprogram at all? What's the huge benefit of that approach?
No, they are not. Decorators don't even exist in JavaScript. Stop assuming typescript is Javascript or even worse, that everybody is on board.
> There's a switch that will change everything on the site from JS to TS globally.
Lol.
The Lit authors tried hard to use vanilla JS everywhere they could, and it shows.
export class SimpleGreeting extends LitElement {
...
}
customElements.define('simple-greeting', SimpleGreeting);It's trivially easy to create Lit components without shadow DOM so I don't really care and use both.
Class fields aren't on the prototype. They're essentially Object.defineProperty() calls that occur right after the super() call of a constructor. You can't get at them at all from the class declaration.
I know more than one way to do something is sometimes a downside, but we have a large audience an a huge portion of it wants to use TypeScript and declarators, and another huge portion of it wants to use vanilla JavaScript. We factored things to give the best DX we could to each group with relatively little cost to us.
As for why metaprogramming, we want a component to update when it's state is changed. Like plain web components, Lit uses classes.
So here, we want setting `el.name` to cause the component to re-render:
class MyElement extends LitElement {
name = 'World';
render() {
return html`<h1>Hello ${this.name}</h1>`
}
}
Decorators actually do the replacement for us, we just have to build the thing to replace it with:
class MyElement extends LitElement {
@property() accessor name = 'World';
render() {
return html`<h1>Hello ${this.name}</h1>`
}
}And yeah, probably they monkey-patched arrays and such, but that was just the way of the world before proxies and native signals. The cool part is Aurelia stuck to web standards, and those “weird mechanisms” were basically polyfills, so even old versions still run solid today, sometimes even faster by leveraging native features.
https://github.com/aurelia/binding/issues/108
> I never used Webpack
That has little to do with Aurelia, and Aurelia itself integrates with Webpack: https://github.com/aurelia/webpack-plugin
> The cool part is Aurelia stuck to web standards, and those “weird mechanisms” were basically polyfills
I could agree that Aurelia looks like you’re sticking to standards¹. If you don’t think about it, then everything kinda works 90% of the time.
But when you actually try to understand what goes on behind the scenes, like you can with React and Angular, there are just so many footguns, especially around composition and reactivity.
Even simple things like passing optional props² or detecting if a <slot> is occupied involved depressing amounts of reverse-engineering.
I’ve heard that Aurelia 2 supposedly fixes many of my issues, but I believe the core idea is beyond fixing. React, Solid and others have more powerful approaches that require fewer concepts to understand.
¹ Although there are still tons of custom concepts and syntax to learn.
Funny you should say that when the current advise for web components is to avoid Shadow DOM (almost like the plague)
> no web components
As in?
> no template strings
Why would React need template strings? React is not the only framework that doesn't use template strings for anything (Vue, Solid, Svelte come immediately to mind). And it's hard to accuse those of being behind the times when Solid is literally the reason for the upcoming native signals proposal
Could you provide the source for this advice?
--- start quote ---
It's worth noting that many of these pain points are directly related to Shadow DOM's encapsulation. While there are many benefits to some types of widely shared components to strong encapsulation, the friction of strong encapsulation has prevented most developers from adopting Shadow DOM, to the point of there being alternate proposals for style scoping that don't use Shadow DOM. We urge browser vendors to recognize these barriers and work to make Shadow DOM more usable by more developers.
--- end quote ---
And probably continued in HTML Web Components https://blog.jim-nielsen.com/2023/html-web-components/
A more technical and measured take on Shadow DOM is here: https://nolanlawson.com/2023/12/30/shadow-dom-and-the-proble...
Yes, there are some people who say to build web components without shadow DOM, but I'm convinced they're only building leaf nodes so they don't need composition with slots. As soon as they try to build any kind of container element they hit big problems.
Can you use style encapsulation and slots without Shadow DOM? Why can't you? I only need the horse, not the horse, and the cart, and the driver, and all the cargo in the cart.
You can't because people pushing all this stuff forward never ever stopped to think whether this was a good idea, and never ever talked to anyone outside of their own group.
[1] I will keep quoting this report by Web Components Working Group to death:
--- start quote --
It's worth noting that many of these pain points are directly related to Shadow DOM's encapsulation. While there are many benefits to some types of widely shared components to strong encapsulation, the friction of strong encapsulation has prevented most developers from adopting Shadow DOM, to the point of there being alternate proposals for style scoping that don't use Shadow DOM. We urge browser vendors to recognize these barriers and work to make Shadow DOM more usable by more developers.
...
Shadow boundaries prevent content on either side of the boundary from referencing each other via ID references. ID references being the basis of the majority of the accessibility patters outlines by aria attributes, this causes a major issue in developing accessible content with shadow DOM. While there are ways to develop these UIs by orchestrating the relationships between elements of synthesizing the passing of content across a shadow boundary, these practices generally position accessible development out of reach for most developers, both at component creation and component consumption time.
...
Selection does not work across or within shadow roots. This makes fully-featured rich-text editors impossible to implement with web components. Some of the web's most popular editors have issues that are blocked on this functionality.
--- end quote ---
Shadow DOM was an absolute pain in reality.
That was our use case and we are migrating away from custom elements to a more conservative approach.
Basically, I'm just curious what a full-stack web component framework with strong defaults could look like. This is primarily a learning exercise, and a way to experiment with integrating web components into modern framework concepts like streaming server components, resumability, automatic serialization, and type-safe RPCs. I don't know if it will ever be production-ready, but I've learned a lot and it's been a ton of fun.
--- start quote ---
I think we're stuck today in a little bit of a rut of extensibility. We wind up leaning on JavaScript to get things, because it is the Turning complete language in our environment. It is the only thing that can give us an answer when CSS and HTML fail us. So we wind up piling ourselves into the JavaScript boat. We keep piling into the JavaScript boat.
Bruce yesterday brought up the great example of an empty body tag, and sort of this pathological case of piling yourself into the JavaScript boat, where you wind up then having to go recreate all of the stuff that the browser was going to do more or less for you if you'd sent markup down the wire in order to get back to the same value that was going to be provided to you if you'd done it in markup. But you did it for a good reason. Gmail has an empty body tag, not because it's stupid. Gmail does that because that's how you can actually deliver the functionality of Gmail in a way that's both meaningful and reliable and maintainable. You wind up putting all of your bets, all of your eggs, into the JavaScript basket.
....
They're the sorts of things that you use when the semantic that you're trying to express is so far away from what HTML natively has a semantic for, that you're willing to go and be completely self served for it. Taking on for yourself accessibility, UI, UX, internationalization, localization, performance, theme ability; all of this stuff is mostly taken care of for you by HTML.
--- end quote ---
14 years later, web components depend on JS to:
- participate in forms
- solve accessibility issues (not yet, but coming through a yet another JS-only standard)
- SSR is still mostly tied to JS and specific JS frameworks (and Declarative Shadow DOM doesn't really solve the issue because it requires you to duplicate a lot of code). See also https://ionic.io/blog/the-quest-for-ssr-with-web-components-...
- CSS modules and other imports that are moved entirely into JS
etc. etc.
-----
Slight off topic. From the same talk:
--- start quote ---
Now, we can do some of that today. We can go and look at the top million pages and figure out which JavaScript library that they're using, which features are being most heavily used, we can put those things in DOM. But is that the right place for them? It's a hard thing to figure out.
--- end quote ---
I wish they spent time figuring that out. We wouldn't have to wait a few decades for https://open-ui.org to slowly make its way into the browsers.
> There is a proposal in TC39 for native signals,
Which originated (or the modern versions of signals originated) in Solid, not in Lit.
Let me quote the readme: https://github.com/tc39/proposal-signals
--- start quote ---
The current draft is based on design input from the authors/maintainers of Angular, Bubble, Ember, FAST, MobX, Preact, Qwik, RxJS, Solid, Starbeam, Svelte, Vue, Wiz, and more…
-- end quote ---
No worries, web components themselves have a very nice critique in the form of their own community report https://w3c.github.io/webcomponents-cg/2022.html listing all the issues that many people had been taking about for literal years before this report.
https://dev.to/ryansolid/web-components-are-not-the-future-4...
https://dev.to/richharris/why-i-don-t-use-web-components-2ci...
https://daverupert.com/2023/07/why-not-webcomponents/
https://paularmstrong.dev/blog/2023/03/11/why-we-do-not-writ...
https://nolanlawson.com/2024/09/28/web-components-are-okay/
https://www.zachleat.com/web/good-bad-web-components/
https://mayank.co/blog/web-components-considered-harmful/
https://adamsilver.io/blog/the-problem-with-web-components/
https://web-highlights.com/blog/are-web-components-dead/
along with some criticisms from very knowledgeable people:
https://x.com/youyuxi/status/1839833110164504691 (author of Vue) https://x.com/Rich_Harris/status/1839785839036887361 (author of Svelte)
Web Components solve a few problems and introduce a few others, use them when they make sense for your needs.
https://github.com/SaleCar/Quasar-UMD-Template
You can do sophisticated things as well eg. Stream half a million Kafka records into the browser- anything available from unpkg or other cdns.
A good cdn UI lib turns out to be https://quasar.dev/
Vue _does_ have some sort of build step, because components use special macros that aren't imported, and the compiler (vite) even complains when you actually import them saying it's not necessary. The build also rewrites your code to some other format that I assume is more optimized because it can do some sort of static analysis.
Are these the main reasons for Vue to use a compiler if it's not necessary? Injecting dependencies and rewriting some code to allow better performance while retaining the nice syntax?
Adding polyfills for older browser targets.
Tree shaking, that is removing code that is not used.
Bundling several files into one to save on requests.
Transpiling, that is, if you want to write code in a different language to javascript eg. Typescript then vite will compile that to javascript.
Linting ie. Reformatting your code to standardise it across developers.
Vulnerability checking, are your dependencies out of date?
Execution of build tasks eg. Preparing static assets like images.
Packaging your app for deployment eg. Zipping
Including logging and hot reload triggers during development.
Bundling environment specific changes eg. Different backend urls if deploying to test envs.
Running unit tests on rebuild to avoid regressions.
Having said all that, the bundling for me is a disadvantage as my own code changes more than 3rd party libs and they are cached. I'm less fussed with types and a lot of the tests and env stuff can be done with a single-file express server for development.
The main advantage for me is that a buildless app will still work correctly in 6 months- permacomputing considerations.
If you can eat the cost to get something in return, it's a nice trade off.
What people using web components want is to get rid of shadowDOM and not feel like they are deviating from the correct path. shadowDOM sucks, stop trying to convince the world that we are using it wrong. shadowDOM is the whole reason web components did not become mainstream (yet?).
All frontend "frameworks" do have some sort of solution to scope CSS to individual components, and without a similar solution, a native component system would not be viable. The implementation has its quirks, but it is a core capability that is necessary for some use cases. For third-party widgets or cross-application components like design systems, the ability to isolate your component from the site it is embedded in is very useful.
Think of shadowDOM as the web component alternative to scoped styles in Vue components (as an example). You don't have to use it, but it would be incredibly inconvenient if it wasn't included in the framework.
Yes. There is just one thing forcing someone to use shadowDOM: slots. You can't use slots without shadowDOM or at least use something like this.children to capture the content inside the <custom-element></custom-element>.
But that is quite the important feature lacking.
It's also possible to import shared CSS in a base class and add it with super.styles() so you don't lose anything.
How else do you achieve that level of encapsulation to enable portable components?
CSS Modules has an established meaning for over a decade, one that is still relevant today. The CSS type imports are very different, and arguably worse.
Call them CSSStyleSheet imports of you need a name suggestion.
Seems like this feature was removed from Chrome.
See https://caniuse.com/mdn-javascript_statements_import_import_...
How is this even supposed to work if each shadow dom has it's own scope of ids? `#id#subid` or something?
What if I want to ref to the outside?
The whole thing is not made for web development.
> People coming from React-land can have a hard time reasoning about the difference between a custom element and a template render function and when best to use each
> This abuse of the component system can indeed lead to a massive explosion in nodes on a page and the performance tanks because of that
I know I certainly have that hard time deciding when I need a custom element and when a render function.
That's not true. Web components that render nothing will contain only their children as nodes, that's good enough for a good amount of container use cases.
So you can have something like:
<uix-modal>
<uix-button icon="wifi"></uix-button>
<dialog>
<div class="flex flex-col gap-4 p-4 w-[640px]">
...
</div>
</dialog>
<uix-modal>
Unless you actually care about the web and its users. Then it turns out it's a very wise advice.
https://w3c.github.io/webcomponents-cg/2022.html
Web Components Community Group: 2022. You are one of the authors:
--- start quote ---
It's worth noting that many of these pain points are directly related to Shadow DOM's encapsulation. While there are many benefits to some types of widely shared components to strong encapsulation, the friction of strong encapsulation has prevented most developers from adopting Shadow DOM, to the point of there being alternate proposals for style scoping that don't use Shadow DOM.
...
Selection does not work across or within shadow roots. This makes fully-featured rich-text editors impossible to implement with web components. Some of the web's most popular editors have issues that are blocked on this functionality
...
Shadow boundaries prevent content on either side of the boundary from referencing each other via ID references. ID references being the basis of the majority of the accessibility patters outlines by aria attributes, this causes a major issue in developing accessible content with shadow DOM.
--- end quote ---
Those are just the tip of the iceberg as these are very explicitly stated in the doc.
Then there's the issues of shifting the responsibility to both developers and consumers to handle Shadow DOM correctly.
Styling/themeing is still pain despite several different specs like shadow parts.
Don't use styles in your components too much, use Javascript to inject CSS into document and shadow trees or else there will be performance impact https://w3c.github.io/webcomponents-cg/2022.html#constructab...
Don't use too many shadow roots or there will be performance impact https://front-end.social/@5t3ph/115135994774490769 (linked in the sibling comment by @azangru)
You can't participate in forms until you write more JS for it, and still your submit buttons will be broken with no solution in sight.
etc. etc.
You don't have to take my word for it. Here's Nolan Lawson, emphasis mine:
--- start quote ---
https://nolanlawson.com/2022/11/28/shadow-dom-and-accessibil...
Shadow DOM is a kind of retcon for the web. As I’ve written in the past, shadow DOM upends a lot of developer expectations and invalidates many tried-and-true techniques that worked fine in the pre-shadow DOM world.
--- end quote ---
Same thing with how css is handled, especially since we have @layer and @scoped now
All there is to say was said years ago. Today it should be enough to know that, for example, "form associated custom elements cannot be a submit button" issue was opened 6 years ago, in 2019: https://github.com/WICG/webcomponents/issues/814
In 2022 web component group report mentions it in passing: https://w3c.github.io/webcomponents-cg/2022.html#concerns-10
That issue is still open.
Or that web components breaking ARIA was known at least 2019: https://x.com/sarahmei/status/1198069119897047041 and this will not be fixed for another 4-5 years at least.
Imagine if any web framework had issues like that.
That doesn't even begin to cover things like "now every useful spec has to be acutely aware of Shadow DOM shenanigans" which delayed any number of specs like scoped CSS etc