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Re: [NavigationTiming2] How many 'navigation' entries are available?

From: Nic Jansma <nic@nicj.net>
Date: Tue, 02 Dec 2014 11:35:49 -0500
Message-ID: <547DEA65.6010906@nicj.net>
To: Ilya Grigorik <igrigorik@google.com>, Jonathan Watt <jwatt@jwatt.org>
CC: public-web-perf <public-web-perf@w3.org>
IE's behavior is to return a single entry for 
performance.getEntriesByType("navigation").  It's the same data as 
performance.timing, though in DOMHighResTimeStamp format and with the 
"name", "duration" and "entryType" values set.

- Nic

On 12/1/2014 5:20 PM, Ilya Grigorik wrote:
> On Thu, Nov 27, 2014 at 11:45 AM, Jonathan Watt <jwatt@jwatt.org 
> <mailto:jwatt@jwatt.org>> wrote:
>     The draft describes the creation of an PerformanceNavigationTiming
>     instance in section 5, but it doesn't seem to say anything about
>     how that object becomes available to scripts. It also doesn't say
>     much about the sequence returned by
>     performance.getEntriesByType("navigation") and what entries are
>     added to it and when they become available.
>     * Are entries from anything other than the last navigation available?
> No, only the current/last navigation is available via performance.timing.
>     * If so, what are the origin restrictions? If a non-same origin
>     navigation
>       happens between two same origin navigations, does the sequence
>     just not
>       contain the non-same origin navigations, or does everything
>     prior to the
>       recent series of same origin navigations not appear in the sequence?
>     * Do new navigations appear at the beginning or end of the sequence?
>     * Does a back/forward destroy previous entries in the series, or just
>       add more to it?
> None of these apply.
>     I'm guessing browser vendors don't want to use memory keeping
>     previous navigation entries around for the rare case that they
>     might be used, so maybe the sequence always only consists of a
>     single entry. If so the spec should say so explicitly though, and
>     if not then the above should be clarified with normative text even
>     if the desired behavior might seem obvious.
> A quick spot check in Chrome and FF shows that both return an empty 
> array for window.performance.getEntriesByType("navigation"). Not sure 
> what we actually want here though... Perhaps for consistency with 
> other events we should return an array with a single entry? I could be 
> convinced either way.
> ig
Received on Tuesday, 2 December 2014 16:36:31 UTC

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