Re: Custom element design with ES6 classes and Element constructors

On Tue, Jan 13, 2015 at 9:50 AM, Domenic Denicola <d@domenic.me> wrote:

> From: Boris Zbarsky [mailto:bzbarsky@mit.edu]
>
> > Just to be clear, this still didn't allow you to upgrade a <my-img> to
> be a subclass of <img>, because that required a change in allocation, right?
>
> Agreed. That needs to be done with <img is="my-img">, IMO. (Assuming the
> upgrading design doesn't get switched to DOM mutation, of course.)
>

Can someone help outline for me exactly why DOM mutation is a problem here?
I can definitely see downsides, but DOM mutation is a fact of life when
scripts are involved on today's web, and it sidesteps a lot of the problems
that we encounter by trying to make in-place upgrading (upgrades without
changing the reference at all) work sanely.

I mean, qSA might not work the way someone might expect, but it also might
not work if you go `$("my-button").button()` using jQuery. What expectation
do we imagine someone has here that we think is missing if we use DOM
mutation (rather than object-model mutation) for upgrades.

-- Yehuda