Re: DOM: innerSmartHTML proposal

Hi,

What is the use case that motivates this change?
Is there a particular example that would significantly benefit from this 
change?

Le 01/07/2014 21:59, Sander Spies a écrit :
> The idea is to create a property, which I will call 'innerSmartHTML' 
> for now, that shares some characteristics with innerHTML, but with 
> some differences:
>
>   * Only change what has really changed (like the ReactJS virtual DOM
>     does)
>     ---
>     So if I have node.innerHTML = "<div><b class="x">something</b></div>";
>
>           and after that say node.innerSmartHTML = "<div><b class="x 
> y">something</b></div>"
>
>           Only the class of b should have been modified, instead of 
> recreating everything as innerHTML does. Of course, adding and 
> removing nodes should also be supported.
What is the "smart" diffing algorithm? It's important that you take the 
time to explain it, otherwise, I don't think browser vendors will be 
convinced to implement it.

React Tree diffing algorithm [1] has a worst case complexity of O(n³) 
(with trade-offs explained at the end to justify a pragmatic choice as 
far as developers are concerned). Browsers implementors are already 
extremely reluctant to implement any O(n²) algorithm, if you're 
proposing something equivalent to React, I don't think this is going to fly.

I'm also not entirely convinced the performance will actually be that 
much better.

>   * perform rendering during requestAnimationFrame
>     ---
>     aggregate all changes to perform them at once, instead of
>     immediately. I understand this will be challenging to do with the
>     current DOM methods in place, but I'm hopeful we can find
>     something that works within the current boundaries of the DOM.
>
I'm afraid you're going to have to give something more concrete than 
"I'm hopeful we can find something that works".
This is a topic that is in implementors mind for some time. They are 
hopeful that something that works can be found too, I hear. But given 
the amount of smart folks thinking of this, I'm afraid the current 
constraints make almost impossible for a simple solution to be found.

> Why do I think this is an interesting idea? Because it significantly 
> simplifies working with the DOM.
I don't understand why it would simplify working with the DOM. You can 
replace innerSmartHTML with innerHTML and you have the current 
situation. I don't see the improvement in "developer ergonomics".

David

[1] http://facebook.github.io/react/docs/reconciliation.html