[whatwg] window.setInterval if visible.

Jeremy Orlow jorlow at chromium.org
Thu Oct 15 13:14:54 PDT 2009

On Thu, Oct 15, 2009 at 12:46 PM, Boris Zbarsky <bzbarsky at mit.edu> wrote:

> On 10/15/09 3:35 PM, Gregg Tavares wrote:
>> I was wondering if there as been a proposal for either an optional
>> argument to setInterval that makes it only callback if the window is
>> visible OR maybe a window.setRenderInterval.
> You might be interested in
> http://groups.google.com/group/mozilla.dev.platform/browse_thread/thread/527d0cedb9b0df7f/57625c94cdf493bffor some more discussion about approaches to this problem.  In particular,
> that proposal tries to address overeager animations in visible windows as
> well.
> Note, by the way, that testing whether a window is "visible" is not cheap;
> testing whether an element is "visible" is even less cheap....

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.  All that
really matters is that the UA never say it isn't visible when any part of
the window is visible.

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