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javascriptsettimeout

What happens to setTimeout when the computer goes to sleep?


In a modern web browser, suppose I do a setTimeout for 10 minutes (at 12:00), and 5 minutes later put the computer to sleep, what should happen when the system wakes up again? What happens if it wakes up before the 10 minutes are up (at 12:09) or much later (at 16:00)?

The reason I'm asking is because I'd like to have a new authentication token requested every 10 minutes, and I'm not sure if the browser will do the right thing and immediately request a new token if it wakes up after a long time.

Clarifications: I don't wan't to use cookies - I'm trying to build a web service here; and yes, the server will reject old and invalid tokens.


Solution

  • As far as I've tested, it just stops and resumes after the computer wakes up. When the computer awakes the setInterval/setTimeout is unaware that any time passed.

    I don't think you should rely on the accuracy of setTimeout/Interval for time critical stuff. For google chrome I discovered recently that any timeout/interval (that is shorter than 1s) will be slowed down to once a second if the tab where it's activated looses focus.

    Apart from that the accuracy of timeouts/intervals is dependent on other functions running etc. In short: it's not very accurate.

    So using interval and timeouts, checking the time against a starttime within the function started by it would give you better accuracy. Now if you start at 12:00, the computer goes to sleep and wakes up at 16:13 or so, checking 16:13 against 12:00 you are certain you have to renew the token. An example of using time comparison can be found here