I'm creating a countdown timer for a project I'm on and I feel its important to get the most accurate time possible. What is more accurate and, more importantly, the most unalterable than server time?
The project requires days/hours/minutes/seconds so if I could grab the exact time the page was requested from the server I could then just throw it in a JavaScript variable and work it out from there.
Since this is run on the server, it gives you the server time.
DateTime currentTime = DateTime.Now;
This you can put in a hidden field on the page and read it with JS when the page loads.
Then, you'll either
need to also know the client time the page loaded so you can calculate how much time has elapsed
OR
have JS increment a counter value that you add to the server time.
With either of these, of course, you're using setTimeout to kick off some JS function.
However, don't forget about time zones!!! Is this important?
One way would be to get the timespan of the difference between the objetive time and current time and then total seconds:
TimeSpan diff = objetiveDateTime - DateTime.Now;
int totalSeconds = diff.TotalSeconds();
Some other way would be to get the objetive date and save it in a js variable in some format js understands (e.g. "October 13, 1975 11:13:00") and then create Date object in js.
Why don't you query a NIST time server? You must consider which stratum your server is on before you assume that the server is a better source than the client. Also consider that you are posting back to a web server, not the DC, which is more often the reference time source for a network. Lastly, if you do not have an authoritative time source to query, consider allowing the user to put in a time hack, or a manual input that would be the difference between your time and the authoritative time.
