In a parallel discussion happening on Mastodon, someone says:

> 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.

[0] - https://front-end.social/@5t3ph/115135994774490769

> As soon as they try to build any kind of container element they hit big problems.

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>

> It's wrong - both that it's general "current advice", and the advice itself when it does pop up.

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 ---