[whatwg] Reliably Minimize Reflows
ian at hixie.ch
Mon Oct 5 19:45:52 PDT 2009
On Sat, 26 Sep 2009, Joseph Pecoraro wrote:
> A task that developers are often faced with is applying many style
> updates to multiple Nodes in the DOM. An example would be
> showing/hiding all divs with the "foo" style class:
> // Hide multiple divs
> var foos = document.getElementsByClassName('foo');
> for (var i=0, len=foos.length; i < len; ++i)
> foos[i].style.display = 'none';
> As I understand it, if there are 20 .foo elements then updating the style on
> each _could_ cause 20 individual reflows.
No, restyling only happens once per event loop cycle, and running a
script takes one event loop cycle. (Unless you force a sync layout by
trying to determine the layout metrics, but nothing does that in the
On Sun, 27 Sep 2009, Boris Zbarsky wrote:
> I would be more interested (from an implementor point of view) in a
> block that said "inside this block, no need to do layout even if I ask
> for layout information". That would provide me with information I don't
> actually have and allow me to optimize better. However, I think it
> would be very difficult to use for authors, because it would be too
Sounds like something for CSSOM, if we add it to the platform at all.
Ian Hickson U+1047E )\._.,--....,'``. fL
http://ln.hixie.ch/ U+263A /, _.. \ _\ ;`._ ,.
Things that are impossible just take longer. `._.-(,_..'--(,_..'`-.;.'
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