W3C home > Mailing lists > Public > public-web-perf@w3.org > July 2014

Re: navigationStart and the actual start of the navigation

From: Reitbauer, Alois <Alois.Reitbauer@ruxit.com>
Date: Wed, 2 Jul 2014 18:35:00 +0000
To: Boris Zbarsky <bzbarsky@MIT.EDU>, Przemys³aw Pietrzkiewicz <ppi@google.com>
CC: "public-web-perf@w3.org" <public-web-perf@w3.org>
Message-ID: <CFD9C8BE.36023%alois.reitbauer@compuware.com>
>From a users perspective the navigation does start once he clicks the
link. Even unload handlers from the point of the user are attributed to
the loading of the next page. Although this might not be correct
technically it is the perceived behaviour by the end user.

What do you think?

// Alois

On 27/06/14 08:53, "Boris Zbarsky" <bzbarsky@MIT.EDU> wrote:

>On 6/27/14, 11:31 AM, Przemys³aw Pietrzkiewicz wrote:
>> I see, thanks for the explanation. In this case, maybe we could go for:
>>
>> "This attribute must return the time when the user agent determines that
>> the navigation will happen. For navigations from documents other than
>> the initial about:blank of the browsing context, this is the time when
>> the user agent finishes prompting to unload the previous document."
>
>Here's a question.
>
>Say I click a link like this: <a target="foo" href="bar">Click me</a>.
>
>The UA decides that a navigation will happen at the point when I click.
>  Then it has to go look for a named target (which might take a while,
>depending on how many frames are reachable from that document).  If it
>finds one it will prompt to unload that document; if not, it will open a
>tab/window/whatever.
>
>Should the time needed to find the named target be considered when
>deciding when navigationStart is?  I guess it can't be if we want to
>exclude the time it takes to fire beforeunload handlers...
>
>> Actually, the second sentence might be redundant - the time when the
>> user agent determines that the navigation will happen in the presence of
>> a document already loaded in the browsing context is the end of
>> beforeunload.
>
>OK...
>
>But initial about:blank can also have beforeunload handlers, note,
>though not in the case when the UA is creating a new browsing context
>and then immediately navigating it.
>
>I guess an important question is this: how is browsing context creation
>fundamentally different from beforeunload handler execution in terms of
>whether it should be included in the time taken to load?  It sounds like
>you want to include the former but exclude the latter, right?
>
>-Boris
>
>P.S. "when the user agent determines that the navigation will happen" is
>a non-testable requirement, fundamentally; UAs can do whatever the heck
>they want with it.
>


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Received on Thursday, 3 July 2014 13:35:14 UTC

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