RE: Visibility API

>From the Microsoft side we agree this is an important dimension to web performance and would like to expand the charter to include these scenarios. We're starting to see hidden and minimized web pages having a significant impact on overall machine performance and power consumption (which we view as a dimension of performance). This feels like an important problem to solve over the next year.

The Tab Visibility API is a good starting point for the visibility aspect of this problem. It would be interesting for the working group to think through what other API's might be important to the scenario - for example API's that explicitly provide battery state and API's that allow websites to more efficiently paint. We think it would be valuable for this working group to look at the problem more holistically and expand our charter to include the pieces needed to address this problem.

Thanks for starting the conversation Arvind. Should we schedule a meeting next week to discuss with members?



From: public-web-perf-request@w3.org [mailto:public-web-perf-request@w3.org] On Behalf Of Arvind Jain
Sent: Wednesday, February 16, 2011 6:30 AM
To: public-web-perf
Subject: Visibility API

Hi webperf folks,

I'd like to check with you if it would make sense to add one more deliverable to the web performance working group.

There's been a proposal for a Tab Visibility API, which provides a web developer an API (in Javascript) to find out whether the page is currently hidden (e.g. not in the foreground tab) vs. visible to the user.
I'm aware of two performance use cases for it:
1) pages that consume a lot of CPU can avoid doing so when the page is not visible to the user.
2) support html5 <link rel=prefetch> standard (when the browser prefetches a page, it should let the page know it's not visible).

Below is the discussion on it on whatwg:

http://lists.whatwg.org/htdig.cgi/whatwg-whatwg.org/2010-December/029382.html

I think it makes sense for web performance working group to standardize this API. Please let me know your thoughts.

Thanks,
Arvind