W3C home > Mailing lists > Public > public-web-perf@w3.org > May 2013

Re: navigationStart in NavigationTiming

From: Arvind Jain <arvind@google.com>
Date: Wed, 1 May 2013 10:23:01 -0700
Message-ID: <CAOYaDdONvNYt0FoDAaAYL5_TE-5u6-f-d8bBsTJSzvLfnOqmAw@mail.gmail.com>
To: Jatinder Mann <jmann@microsoft.com>
Cc: public-web-perf <public-web-perf@w3.org>
I opened http://en.wikipedia.org link from http://www.wikipedia.org in
Chrome using right click->open in new tab option and here is what I got:


   1. connectEnd: 1367368521147
   2. connectStart: 1367368521147
   3. domComplete: 1367368522013
   4. domContentLoadedEventEnd: 1367368521818
   5. domContentLoadedEventStart: 1367368521818
   6. domInteractive: 1367368521818
   7. domLoading: 1367368521244
   8. domainLookupEnd: 1367368521147
   9. domainLookupStart: 1367368521147
   10. fetchStart: 1367368521147
   11. loadEventEnd: 1367368522016
   12. loadEventStart: 1367368522013
   13. navigationStart: 1367368521062
   14. redirectEnd: 1367368521147
   15. redirectStart: 1367368521062
   16. requestStart: 1367368521149
   17. responseEnd: 1367368521231
   18. responseStart: 1367368521230
   19. secureConnectionStart: 0
   20. unloadEventEnd: 0
   21. unloadEventStart: 0


As you can see, navigationStart != fetchStart and includes the redirect
time, and redirect timings are not zeroed out.

Arvind



On Wed, May 1, 2013 at 9:54 AM, Arvind Jain <arvind@google.com> wrote:

> Why are redirect timings zeroed out for this same origin redirect?
>  On May 1, 2013 9:27 AM, "Jatinder Mann" <jmann@microsoft.com> wrote:
>
>>  Can you submit a test case? In this example, redirectStart and
>> redirectEnd have been zero’d out. An example where they aren’t zero’d out
>> might be more helpful. ****
>>
>> ** **
>>
>> Thanks,****
>>
>> Jatinder****
>>
>> ** **
>>
>> *From:* Arvind Jain [mailto:arvind@google.com]
>> *Sent:* Tuesday, April 30, 2013 7:08 PM
>> *To:* public-web-perf
>> *Subject:* navigationStart in NavigationTiming****
>>
>> ** **
>>
>> I've a question about the definition of navigationStart in the
>> specification (
>> http://www.w3.org/TR/navigation-timing/#dom-performancetiming-navigationstart
>> )****
>>
>> ** **
>>
>> It says:****
>>
>> This attribute must return the time immediately after the user agent
>> finishes prompting to unload<http://www.w3.org/TR/html5/browsers.html#prompt-to-unload-a-document> the
>> previous document. If there is no previous document, this attribute must
>> return the same value as fetchStart<http://www.w3.org/TR/navigation-timing/#dom-performancetiming-fetchstart>
>> .****
>>
>> ** **
>>
>> The second part of this statement seems odd to me. In case the document
>> in question has redirects (e.g. same origin redirects), the value of
>> navigationStart will be very different if there was a previous document
>> that had to be unloaded vs. not.****
>>
>> ** **
>>
>> The difference doesn't make sense.****
>>
>> ** **
>>
>> This line was added on Oct 14. 2010. There is one discussion a day before
>> that****
>>
>> http://lists.w3.org/Archives/Public/public-web-perf/2010Oct/0024.html****
>>
>> which seems to have better text for this but the spec has something else.
>> ****
>>
>> ** **
>>
>> I think this inconsistency happened as we revised the definition of
>> navigationStart, and we forgot to update the second part of the definition.
>> ****
>>
>> ** **
>>
>> I checked Chrome and it does the right thing - I load
>> http://en.wikipedia.org/ in a new tab and it has a same origin redirect.
>> navigationStart is not equal to fetchStart in this case, and in fact occurs
>> before redirectStart which in my opinion is correct behavior.****
>>
>> ** **
>>
>> How do we fix this?****
>>
>> ** **
>>
>> Arvind****
>>
>
Received on Wednesday, 1 May 2013 17:23:29 UTC

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