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As seen in the screenshot above, for the last resource loaded, there is an id that identifies me. I would like to use the JSON response in my personal dashboard application. What is that id, and how often does it change?

Oh and now that I have publicly posted it, how confidential is it supposed to be?

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@NullUserExceptionอ_อ Ok right, and the page loads even without that id. I don't have to worry about CORS, I have loaded an extension with elevated privileges and can load any url in my dashboard with my cookies and session data attached. Can you add it as an answer so that i can accept it? Thanks! – Achshar Feb 8 '13 at 18:21
Actually, I was thinking about something else. That particular "ID" looks like a UNIX timestamp (milliseconds from UNIX epoch). It converts to this date and time: 2013-02-08 18:05:43 UTC, which was just a few minutes before you made this post. – NullUserException อ_อ Feb 8 '13 at 18:23
@NullUserExceptionอ_อ hmm in any case, it is not required to load the JSON response which is all i mean to know. Thanks for the help! – Achshar Feb 8 '13 at 18:29
I believe it's there to ensure your browser doesn't cache any of it. – NullUserException อ_อ Feb 8 '13 at 18:31
@NullUserExceptionอ_อ Just to be nitpicking, a unix timestamp counts the number of seconds, not milliseconds, since the eopch. JavaScript is a bit special in that regard :) – balpha Feb 8 '13 at 20:02
up vote 8 down vote accepted

It's neither confidential, nor is it an ID, nor does it identify you.

That number comes from jQuery, it is appended to the URL here and created here, and it is nothing more than the number of milliseconds that have passed since January 1st 1970, 0:00 UTC, according to your computer's clock.

This parameter is there because that AJAX request is made with jQuery's AJAX option cache set to false, to prevent your browser from showing you outdated cached data and instead force it to pull fresh content from the server. This goal is achieved by appending this meaningless (but unique) parameter to the URL, so to your browser it looks like it's a totally new URL that it has never seen before.

The server doesn't care about this number; it completely ignores it.

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That ID is only unique until 2038. – 11684 Feb 9 '13 at 9:27
Nope, @11684, JavaScript's integer is 64 bit. And if it were 32 bit, it would roll over every 25 days as we're talking microseconds here? And all that aside, even if a "true" 32 bit Unix timestamp were used, and it would go negative in 2038, it would still be unique until about July 2144‌​, for those who visited the site every second since the private beta, and never cleared their cache... ;-) – Arjan Feb 9 '13 at 11:07
As an aside: my Chrome's about:cache is listing all copies of those stats it has ever fetched. Firefox seems to do the same, though it also marks all with "Expires: 1970-01-01 01:00:00". So, maybe changing Cache-Control: private into no-cache or no-store would be nice, if that's in your control? (I know these entries only take little space on disk, but no idea how mobile browsers handle this—like they might wipe other cached entries if the cache fills up? In Firefox, I just logged in for the first time after clearing its cache, so it only shows today's entries; same after restart.) – Arjan Feb 9 '13 at 14:32

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