Tags: extensibility

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Extensibility

I’ve said it before, but I’m going to reiterate my conflicted feelings about Web Components:

I have conflicting feelings about Web Components. I am simultaneously very excited and very nervous.

There are broadly two ways that they could potentially be used:

  1. Web Components are used by developers to incrementally add more powerful elements to their websites. This evolutionary approach feels very much in line with the thinking behind the extensible web manifesto. Or:
  2. Web Components are used by developers as a monolithic platform, much like Angular or Ember is used today. The end user either gets everything or they get nothing.

The second scenario is a much more revolutionary approach—sweep aside the web that has come before, and usher in a new golden age of Web Components. Personally, I’m not comfortable with that kind of year-zero thinking. I prefer evolution over revolution:

Revolutions sometimes change the world to the better. Most often, however, it is better to evolve an existing design rather than throwing it away. This way, authors don’t have to learn new models and content will live longer. Specifically, this means that one should prefer to design features so that old content can take advantage of new features without having to make unrelated changes. And implementations should be able to add new features to existing code, rather than having to develop whole separate modes.

The evolutionary model is exemplified by the design of HTML 5.

The revolutionary model is exemplified by the design of XHTML 2.

I really hope that the Web Components model goes down the first route.

Up until recently, my inner Web Components pendulum was swinging towards the hopeful end of my spectrum of anticipation. That was mainly driven by the ability of custom elements to extend existing HTML elements.

So, for example, instead of creating a new element like this:

<taco-button>...</taco-button>

…you can piggyback off the existing semantics of the button element like this:

<button is="taco-button">...</button>

For a real-world example, see Github’s use of <time is="time-ago">.

I wrote about creating responsible Web Components:

That means we can use web components as a form of progressive enhancement, turbo-charging pre-existing elements instead of creating brand new elements from scratch. That way, we can easily provide fallback content for non-supporting browsers.

I’d like to propose that a fundamental principle of good web component design should be: “Where possible, extend an existing HTML element instead of creating a new element from scratch.”

Peter Gasston also has a great post on best practice for creating custom elements:

It’s my opinion that, for as long as there is a dependence on JS for custom elements, we should extend existing elements when writing custom elements. It makes sense for developers, because new elements have access to properties and methods that have been defined and tested for many years; and it makes sense for users, as they have fallback in case of JS failure, and baked-in accessibility fundamentals.

But now it looks like this superpower of custom elements is being nipped in the bud:

It also does not address subclassing normal elements. Again, while that seems desirable the current ideas are not attractive long term solutions. Punting on it in order to ship a v1 available everywhere seems preferable.

Now, I’m not particularly wedded to the syntax of using the is="" attribute to extend existing elements …but I do think that the ability to extend existing elements declaratively is vital. I’m not alone, although I may very well be in the minority.

Bruce has outlined some use cases and Steve Faulkner has enumerated the benefits of declarative extensibility:

I think being able to extend existing elements has potential value to developers far beyond accessibility (it just so happens that accessibility is helped a lot by re-use of existing HTML features.)

Bruce concurs:

Like Steve, I’ve no particularly affection (or enmity) towards the <input type="radio" is="luscious-radio"> syntax. But I’d like to know, if it’s dropped, how progressive enhancement can be achieved so we don’t lock out users of browsers that don’t have web components capabilities, JavaScript disabled or proxy browsers. If there is a concrete plan, please point me to it. If there isn’t, it’s irresponsible to drop a method that we can see working in the example above with nothing else to replace it.

He adds:

I also have a niggling worry that this may affect the uptake of web components.

I think he’s absolutely right. I think there are many developers out there in a similar position to me, uncertain exactly what to make of this new technology. I was looking forward to getting really stuck into Web Components and figuring out ways of creating powerful little extensions that I could start using now. But if Web Components turn out to be an all-or-nothing technology—a “platform”, if you will—then I will not only not be using them, I’ll be actively arguing against their use.

I really hope that doesn’t happen, but I must admit I’m not hopeful—my inner pendulum has swung firmly back towards the nervous end of my anticipation spectrum. That’s because I’m getting the distinct impression that the priorities being considered for Web Components are those of JavaScript framework creators, rather than web developers looking to add incremental improvements while maintaining backward compatibility.

If that’s the case, then Web Components will be made in the image of existing monolithic MVC frameworks that require JavaScript to do anything, even rendering content. To me, that’s a dystopian vision, one I can’t get behind.

The complexity of HTML

Baldur Bjarnason has written down his thoughts on why he thinks HTML is too complex.

Now we’re back to seeing almost the same level of complexity and messiness in most web pages as we saw in the worst days of table-hacking. The semantic elements from HTML5 are largely unused.

The reason for this, as outlined in an old email by Matthew Thomas, is down to the lack of any visible benefit from browsers:

unless there is an immediate visual or behavioural benefit to using an element, most people will ignore it.

That’s a fair point, but I think it works in the opposite direction too. I’ve seen plenty of designers and developers who are reluctant to use HTML elements because of the default browser styling. The legend element is one example. A more recent one is input type=”date”—until there’s a way for authors to have more say about the generated interface, there’s going to be resistance to its usage.

Anyway, Baldur’s complaint is that HTML is increasing in complexity by adding new elements—section, article, etc.—that provide theoretical semantic value, without providing immediate visible benefits. It’s much the same argument that informed Cory Doctorow’s Metacrap essay over a decade ago. It’s a strong argument.

There’s always a bit of a chicken-and-egg situation with any kind of language extension designed to provide data structure: why should authors use the new extensions if there’s no benefit? …and why should parsers (like search engines or browsers) bother doing anything with the new extensions if nobody’s using them?

Whether it’s microformats or new HTML structural elements, the vicious circle remains the same. The solution is to try to make the barrier to entry as low as possible for authors—the parsers/spiders/browsers will follow.

I have to say, I share some of Baldur’s concern. I’ve talked before about the confusion between section and article. Providing two new elements might seem better than providing just one, but in fact it just muddies the waters and confuses authors (in my experience).

But I realise that in the grand scheme of things, I’m nitpicking. I think HTML is in pretty good shape. Baldur said “simply put, HTML is a mess,” and he’s not wrong …but HTML has always been a mess. It’s the worst mess except for all the others that have been tried. When it comes to markup, I think that “perfect” is very much the enemy of “good” (just look at XHTML2).

When I was in San Francisco back in August, I had a good ol’ chat with Tantek about markup complexity. It started when he asked me what I thought of hgroup.

I actually found quite a few use cases for hgroup in my own work …but I could certainly see why it was a dodgy solution. The way that a wrapping hgroup could change the semantic value of an h2, or h3, or whatever …that’s pretty weird, right?

And then Tantek pointed out that there are a number of HTML elements that depend on their wrapper for meaning …and that’s a level of complexity that doesn’t sit well with HTML.

For example, a p is always a paragraph, and em is always emphasis …but li is only a list item if it’s wrapped in ul or ol, and tr is only a table row if it’s wrapped in a table.

(Interestingly, these are the very same elements that browsers will automatically adjust the DOM for—generating ul and table if the author doesn’t include it. It’s like the complexity is damage that the browsers have to route around.)

I had never thought of that before, but the idea has really stuck with me. Now it smells bad to me that it isn’t valid to have a figcaption unless it’s within a figure.

These context-dependent elements increase the learning curve of HTML, and that, in my own opinion, is not a good thing. I like to think that HTML should be easy to learn—and that the web would not have been a success if its lingua franca hadn’t been grokabble by mere mortals.

Tantek half-joked about writing HTML: The Good Parts. The more I think about it, the more I think it’s a pretty good idea. If nothing else, it could make us more sensitive to any proposed extensions to HTML that would increase its complexity without a corresponding increase in value.