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Re: [JSPreflight] - First Draft of JavaScript Preflight Injection online

From: Ilya Grigorik <igrigorik@google.com>
Date: Wed, 31 Jul 2013 16:48:10 -0700
Message-ID: <CADXXVKqU8ROsyfRm3WSr7DnsFKcAdRtnvuy0vaJj31UKU3k+1g@mail.gmail.com>
To: "Reitbauer, Alois" <Alois.Reitbauer@compuware.com>
Cc: "public-web-perf@w3.org" <public-web-perf@w3.org>
   - The monitoring JavaScript becomes a single point of failure for the
   page if it does not load
   - Modification of page source can result in unwanted side effects
   - The monitoring JavaScript will not be loaded when the page cannot be
   loaded (e.g. because of a DNS error).
   - It does not allow to collect performance data for non-HTML request
   (e.g. images, pdf downloads)

The first two seem contrived.. we all know that these scripts should be
loaded in an async way, and we have well defined mechanisms to do so. And
isn't the last point intentional and handled by ResourceTiming?

Really, it seems like the only new functionality here is point #3, which is
error reporting for pages which failed to load? Which is a valid and
interesting case, but having said that, do we have any idea or data on how
frequently this occurs in the wild? I know this may be a chicken and the
egg question, but I'm curious if the extra machinery (and another
cookie-like mechanism is pretty heavy), is really warranted.

ig





On Mon, Jul 22, 2013 at 2:37 AM, Reitbauer, Alois <
Alois.Reitbauer@compuware.com> wrote:

>  The first draft of the JavaScript Preflight Injection Specification is
> available. The goal of this specification is to provide a reliable means
> for collecting performance data in the browser without affecting page
> behaviour. You can find the latest version at
> http://w3c-test.org/webperf/specs/JSPreflightInjection/. Comments and
> contributions are welcome.
>
>  // Alois
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Received on Wednesday, 31 July 2013 23:49:17 UTC

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