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

On Wed, Aug 7, 2013 at 12:36 AM, Reitbauer, Alois <Alois.Reitbauer@compuware.com<mailto:Alois.Reitbauer@compuware.com>> wrote:
[Alois] If it were that simple :-). In the general case you are right and that's what we do today. However, there are tons of cases where this breaks the page. I can provide some real world examples where this gets really tricky to impossible.

Please do, curious...

[Alois]

There are a lot of examples and we needed to build an extensive rule set to cover this at first sight simple problem. First of all you will have to wait after all meta tags. Executing JavaScript before meta tags might break the page. Another problem are base tags. You have to wait until after the base tag as it would not work any more otherwise. This means you have to block flushing the content until you reached a point where you are sure that these cannot occur anymore.




 This approach is also not applicable to the case where the page cannot be loaded.

Correct. I do agree that we need an error reporting mechanism, but (in my opinion), this proposal couples error reporting with a much heavier and unnecessary injection mechanism - we're adding another cookie mechanism, a full blocking JS resource, and a bunch of other complications. Which is why I'm suggesting a simpler, CSP-like implementation: on error, beacon some predefined error report to provided URL.

[Alois] The CSP case is very different from performance monitoring. How would this be able to cover single-page web apps?

ig
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