Re: Ready indicator

Isn't this use case covered by the User Timing API
<http://www.html5rocks.com/en/tutorials/webperformance/usertiming/>? (with
perhaps adding some convention on a common "web app loaded" event)

On Fri, Oct 10, 2014 at 7:08 PM, Eli Perelman <eperelman@mozilla.com> wrote:

> Hello,
>
> In my experiences working on tooling for performance on Firefox OS, I have
> run into a difficult situation in timing the launch time of various
> applications. These applications are built using Web-standard technologies,
> e.g. JavaScript, CSS, and HTML (as such I may use app and site
> interchangably). In order to effectively measure the amount of time an
> application took to launch, I would need to know at which moment the
> application is loaded. Using standard web technologies in the past, we
> would often rely on indicators of window load or the last tick of the event
> loop to determine that everything has been completed, but unfortunately in
> today's world of dynamic loading, this just isn't deterministic.
>
> There is no reliable way to *infer* the loading time of an application,
> or any website for that matter. Each instance has the power to defer
> loading of all, some, or none of their assets. The window load event does
> not represent a state in every site or app that deems it usable from a user
> standpoint. By using an arbitrarily-inferred event for assessing launch
> performance, engineers are encouraged to defer as much loading as possible
> in an effort to thwart timing metrics.
>
> I believe that if we cannot infer this "ready" state of a site, then the
> site must have the power to *imply* it. By introducing a performance API
> where a site can infer what it determines to be its "ready" state, we can
> provide better value to tooling by making metrics more directly correlated
> with user-perceived launching. It also has greater use cases outside of
> just performance tooling, as it can be used as an indicator to engines to
> possibly optimize the loading of content or even updating its UI in a more
> intelligent fashion. It would also encourage developers to load assets in
> the manner that makes sense for them in the development process, and not
> destroying their workflow for the sake of "boosting the numbers".
>
> For Gecko, we believe this would be interesting to implement, and can
> propose a possible API if this group finds interest in exploring the idea.
> We would also be interested to discover if there is any prior art in this
> domain.
>
>
> Thanks,
>
> *Eli Perelman*
> Software Engineer, Firefox OS
>