Re: [webcomponents] Auto-creating shadow DOM for custom elements

On Dec 7, 2013, at 8:33 PM, Rafael Weinstein <rafaelw@google.com> wrote:
> On Sat, Dec 7, 2013 at 6:56 PM, Ryosuke Niwa <rniwa@apple.com> wrote:
> 
> > On Dec 7, 2013, at 3:53 PM, Rafael Weinstein <rafaelw@google.com> wrote:
> >
> > The issue is that being an element and having shadow DOM -- or any display DOM, for that matter -- are orthogonal concerns.
> >
> > There are lots of c++ HTML elements that have no display DOM. Polymer already has an even larger number.
> 
> While that's true in browser implementations, there is very little authors can do with a plain element without any shadow content it since JavaScript can't implement it's own style model (i.e. creating a custom frame object in Gecko / render object in WebKit/Blink) or paint code in JavaScript.
> 
> If the only customization author has to do is adding some CSS, then we don't need custom element hook at all.
> 
> 
> I'm was thinking about elements whose purpose isn't presentational. For example, <link> or <script> in html, or <polymer-ajax> in polymer.

What are advantages of using an element to represent an AJAX request over, say, doing so in JSON or via function call?

e.g.
Polymer.ajax({url: "http://gdata.youtube.com/feeds/api/videos/", params: '{"alt":"json", "q":"chrome"}', handleAs: 'json', onResponse=handleResponse})

instead of

<polymer-ajax auto url="http://gdata.youtube.com/feeds/api/videos/" 
    params='{"alt":"json", "q":"chrome"}'
    handleAs="json"
    on-polymer-response="{{handleResponse}}">
</polymer-ajax>

It seems strange to have a node in DOM whose sole job is to issue an XHR request and call a handler.

Having said that, I could imagine people implementing link[rel=import] like feature using some custom element as a polyfill for a yet-to-be implemented browser feature.

- R. Niwa