Re: navigationStart and the actual start of the navigation

The goal of the spec was to get developers full insight into how long
it took the page to load once the browser started to navigate to the
page as well as how much the user perceived latency was.

So ideally, it'd be good to report the time starting from when the
user clicks, and report the breakdown (time it took to unload the
previous page, create the new tab etc.).

Just like spawning renderer takes time, there are other situations
e.g. the network on the phone may be down and you have to bring it up.
In navigation timing 2, we added a metric called
linkNegotiation{Start|End} to capture that. In that case, responseEnd
- navigationStart would capture the total time the user waited and the
developer can subtract the linkNegotiation time from it if he wants

So if possible, it would be good to have navigationStart refer to when
the user expresses intent to navigate by clicking and then track the
time to unload previous document, bring up the network and start the
renderer in the included metrics. I'm not sure how to capture it.

On Tue, Jul 1, 2014 at 9:30 AM, Boris Zbarsky <> wrote:
> On 7/1/14, 12:27 PM, Boris Zbarsky wrote:
>> The user clicks a button.
> Mouse button, that is.  After which there is OS and UA event loop lag before
> DOM click event dispatch happens.
> -Boris

Received on Tuesday, 1 July 2014 19:10:51 UTC