[whatwg] window.setInterval if visible.

[Boris Zbarsky]

On 10/15/09 4:14 PM, Jeremy Orlow wrote:
> I'd imagine that UAs could use an overly conservative metric of when
> things are visible to make things cheaper if/when this is a concern.

It's a concern any time someone's checking it every 10ms interval 
invocation.  For example, I'm right now looking at a browser window 
where the check would probably take longer than that (ping time from the 
X client to the X server is 50ms in this case).

> I agree that some mechanism to know when things aren't visible would be
> very useful.

What are the use cases?  Are they addressed by roc's proposal?  If not, 
is an explicit script-triggered visibility check the only way to address 
them?

-Boris