Re: [PageVisibility] What should the visibility api return in display:none iframes?

On Mon, Oct 10, 2011 at 10:26 AM, Shishir Agrawal <> wrote:
> We started discussing the spec as a way for pages to figure out how they
> were embedded in the browser: foreground tab, background tab etc. I dont
> think we should implement the display:none case because,

As always, the way we should look at the feature set for the spec is
from use cases, not from technical point of view, but from the point
of view of what application behavior we're trying to support.

One concrete example that I've always thought of is the bugzilla build
reporting webpage [1]. This page uses a fair amount of resources as it
updates itself every few minutes. It downloads a few JSON objects,
parses those, and based on the result makes yet other requests.
Finally it uses the result of those requests to build a DOM and
display to the user.

I often want to keep a tab open with this page for easy access.
However if I'm not actively looking at the page, the page could save
quite a bit of resources by downloading data less often, and when
downloading, not go through the hassle of building the DOM needed for
display. Hence that page should check .hidden and act accordingly.

If someone creates a dash-board page which shows the status of several
different developer tools in separate iframes, and lets the user hide
and redisplay various tools, it would make a lot of sense to me to in
this case try to save processing resources. If we flag any documents
inside the display:none iframe as .hidden, we would automatically get
the desired resource savings.


> - Keeping the spec simple - ensures that the spec is implemented
> consistently. The more complicated we make the spec, we may see vendors
> diverge from it.

I agree spec simplicity is important. But it doesn't seem like this is
adding a lot of implementation burden (in the Firefox case, it was the
developer implementing the feature who found this spec-"flaw" and
suggested the fix). Definitely not enough burden that I'd be worried
about implementation divergence.

> - The discussion to include some cases - such as display:none and not others
> like visibility:hidden, or pages hidden by window seem a bit arbitrary to
> me. Like I mentioned this was also not the intended use of the initial spec
> (ofcourse that can change).

Display:none is definitely a stronger styling change other properties.
For example it's the only CSS property discussed so far which affects
all media types per the CSS2.1 specification (display and various
content-creating properties are in fact the only ones that do).

So far the only technical argument presented against taking
display:none into account is implementation burden. However IMO
website utility is more important.

/ Jonas

Received on Monday, 10 October 2011 18:59:58 UTC