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I'm writing a web application (HTML/CSS/JS frontend, C# backend) where the users are expected to be on the same page for a while (usually longer than 10 minutes). I would like to periodically check the server to see if the user's session has expired. Is there any disadvantage to using setInterval with an interval of say, 2 - 5 minutes, to make an AJAX request to the server?

mittmemo
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2 Answers2

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No, there is no disadvantage. However, the timer isn't the most accurate. See also: Will setInterval drift? This may not matter to you, as it is a bigger problem for timers fired rapidly. Plus, it doesn't soundl ike exact timing is a problem for you either.

Community
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Brad
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  • Thanks for the answer! You are correct, accuracy isn't a problem for me. I just need it to happen roughly every few minutes. – mittmemo Aug 13 '12 at 17:00
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There is no problem in doing that. There will be a performance issue only when you don't keep the interval ids and run a number of intervals simultaneously (especially when the delay is very less). To prevent this you can clear the current interval before creating a new one. This makes sure that there is only required interval is live.

clearInterval(intervalID);
intervalID = setInterval(function(){
   ...
}, 100);
Diode
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  • Thanks! That's what I figured: multiple concurrent timers present performance issues. Just wanted to be sure! – mittmemo Aug 13 '12 at 17:04