> The pro-web-component folks argue that WCs are standardised and will continue to work basically indefinitely regardless of the ebbs and flows of popular libraries, and because it's easier to progressively enhance and therefore more accessible. This is correct, and those points are valuable if what you seek is a way to add resilient islands of interactivity to your document.
I'm not sure that's even that correct. If you write code using browser APIs that are currently standardised, your code will work indefinitely, whether or not you use Web Components, React, or jQuery. Hell, we used to have jQuery-based components with the whole $(...).datepicker() system. Yes, it has its flaws, but it'll still work today if that's what your want from it.
Secondly, I don't think Web Components do work well from a progressive enhancement perspective. Progressive enhancement is starting from the bare minimum (i.e. just HTML and some styles, if that), and progressively adding features to that initial state that don't prevent any of the previously-added features from working. So you start with an HTML form skeleton, and you add some validation attributes, you add an event handler that calls fetch instead of reloading the page, you extend the address input so that it suggests real addresses - but the whole time, the HTML form is still there and it still works.
But without Javascript, Web Components are essentially empty holes that can't do anything. They don't progressively enhance anything. You can to a certain extent wrap existing elements, you can take the isomorphic approach described in this post, etc. But even when you do that, the browser will replace the contents of the element with the component's rendered output when the Javascript comes online, potentially deleting any user inputs if they'd interacted with the previous context. If your aim is true progressive enhancement, you should probably look in a different direction.
In fairness, I don't disagree that these claims are often made by Web Component proponents. But I think they're the wrong claims to be making. Web Components seem to be most useful if you're trying to isolate a complex stateful component written by one person or team and ended it into a complex stressful application written by a different person or team. They're essentially like lightweight iframes. This is really useful, and should be promoted more - but it's also quite a specific use.
> I'm not sure that's even that correct. If you write code using browser APIs that are currently standardised, your code will work indefinitely, whether or not you use Web Components, React, or jQuery.
The most charitable interpretation of this argument is that framework specific component libraries assume for the most part that you're using that specific framework. The documentation for popular React component libraries like shadcn are largely incomprehensible if you're not using React. Libraries like Shoelace (now being renamed to Web Awesome) make no such assumptions. You can just drop a script tag into your page's markup and get started without having to care about (or even be aware of) the fact that Shoelace uses Lit internally.
> But without Javascript, Web Components are essentially empty holes that can't do anything. They don't progressively enhance anything.
This is not true if you're using the new Declarative Shadow DOM API [1]. You literally just add a template tag with a shadowroot mode attribute inside your custom element, and then the component works without JavaScript. When (or if) the JavaScript loads, you simply check for the existence of a server-rendered shadow root using `internals.shadowRoot`. If a shadow root already exists then you don't have to replace anything, and you can attach your event listeners to the pre-existing shadow root (i.e. component hydration).
The only reason I avoid linking to that MDN page is because I think it does a bad job of actually assembling all of the pieces together into a working example. That's why I linked specifically to the component hydration section, which assembles it all into a functioning component complete with an actual class and constructor. The code example in that specific section doesn't appear to use any deprecated or non-standard features. Otherwise, I normally do prefer MDN as an authoritative source of documentation.
The MDN page has the deprecation notice for the `shadowRoot` property.
Yes, the examples on your page are way more comprehensive. Even with compatibility support for old Chrome versions. Unfortunately, that support example will also break your code on other browsers.
People may want to read it anyway, and just fix the problem. It being outdated doesn't make the explanation bad.
What's deprecated is the `shadowroot` attribute on the template element, which the example I linked to does not use. The second line of code in that example is `<template shadowrootmode="open">`.
All of this is mentioned at the very top of the article where it says: "Note that the specification for this feature changed in 2023 (including a rename of shadowroot to shadowrootmode), and the most up to date standardized versions of all parts of the feature landed in Chrome version 124."
> Unfortunately, that support example will also break your code on other browsers.
> You literally just add a template tag with a shadowroot mode attribute inside your custom element, and then the component works without JavaScript.
Wtf is a shadowroot?
I'm of increasing confidence that the entire project to unify document display and application runtime has utterly failed and there's no way (and no benefit) to resuscitate it. We need two different internets: one for interactive applications and one for document browsing.
In the Document Object Model (DOM), every document has a root node, which you can retrieve by calling `getRootNode()` on any node in the document (e.g. `document.getRootNode()` or `document.body.getRootNode()`).
Custom Elements can have their own "shadow" document that's semi-isolated from the parent document, and the root node of that shadow document is called the shadow root.
The idea is to be able to create your own HTML elements (which also have their own hidden DOM). If you enable a setting in Chrome's Devtools (Show user agent shadow DOM) [1], you can actually see the hidden shadow structure of built in HTML Elements: https://www.youtube.com/watch?v=Vzj3jSUbMtI&t=291s
I'm not sure that's even that correct. If you write code using browser APIs that are currently standardised, your code will work indefinitely, whether or not you use Web Components, React, or jQuery. Hell, we used to have jQuery-based components with the whole $(...).datepicker() system. Yes, it has its flaws, but it'll still work today if that's what your want from it.
Secondly, I don't think Web Components do work well from a progressive enhancement perspective. Progressive enhancement is starting from the bare minimum (i.e. just HTML and some styles, if that), and progressively adding features to that initial state that don't prevent any of the previously-added features from working. So you start with an HTML form skeleton, and you add some validation attributes, you add an event handler that calls fetch instead of reloading the page, you extend the address input so that it suggests real addresses - but the whole time, the HTML form is still there and it still works.
But without Javascript, Web Components are essentially empty holes that can't do anything. They don't progressively enhance anything. You can to a certain extent wrap existing elements, you can take the isomorphic approach described in this post, etc. But even when you do that, the browser will replace the contents of the element with the component's rendered output when the Javascript comes online, potentially deleting any user inputs if they'd interacted with the previous context. If your aim is true progressive enhancement, you should probably look in a different direction.
In fairness, I don't disagree that these claims are often made by Web Component proponents. But I think they're the wrong claims to be making. Web Components seem to be most useful if you're trying to isolate a complex stateful component written by one person or team and ended it into a complex stressful application written by a different person or team. They're essentially like lightweight iframes. This is really useful, and should be promoted more - but it's also quite a specific use.