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Re: NavigationTiming event for initial display

From: Bryan McQuade <bmcquade@google.com>
Date: Thu, 23 Jun 2016 15:12:43 +0000
Message-ID: <CADLGQyDcL0H9W+XZF8HhmF6UNXriJ1WpUb1jYCw1TKqhATnKrg@mail.gmail.com>
To: Stefan Seifert <nine@detonation.org>, public-web-perf <public-web-perf@w3.org>, paulirish@google.com, Shubhie Panicker <panicker@google.com>
Thanks for starting this discussion. This has been an area of interest
recently, and I believe there's a desire to expose display-oriented metrics
to the web platform. +Paul Irish <paulirish@google.com> has been working on
some possible display-oriented metrics and may be able to share more about
this.

We do currently expose a first paint timing
via chrome.loadTimes().firstPaintTime, however chrome.loadTimes() is an
old, non-standard API and we're hoping to standardize some paint/display
timing information and then deprecate chrome.loadTimes().

IIUC IE also exposes a similar performance.timing.msFirstPaint.

So there's no standard APIs available today, but I agree there should be.
Paul can share more about the thinking with progressive web metrics.

On Thu, Jun 23, 2016 at 9:13 AM Stefan Seifert <nine@detonation.org> wrote:

> Hi!
>
> Trying to bring facts into a discussion about the merits and harm of using
> Javascript to lazily load images, I've been looking through the
> documentation
> about timing interfaces. While Navigation Timing seems to offer a wealth of
> information, the one point that would be most helpful for me is the time to
> initial display, i.e. when the browser first displays rendered content.
>
> This is the time, people try to optimize by using lazy image loaders which
> then rob the browser any chance to make a better informed decision based on
> all the information it has. The first step in optimization is of course
> creating a reliable and meaningful benchmark. In absence of timing
> information
> offered by the browser (which should be the entity that knows best), people
> have to resort to opaque web services claiming to use elaborate camera
> setups
> or even worse - tribal knowledge spread at conferences and in blog posts.
>
> Would it be feasible to add such an event to Navigation Timing or is this
> information already available in some form?
>
> Thanks and regards,
> Stefan Seifert
>
>
>
Received on Thursday, 23 June 2016 15:13:55 UTC

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