My stopwatch script runs flawlessly in the background on Android (counting up the time), but iOS 4.3.2 seems to pause the script. On iOS the stopwatch stops at the time where the application was sent to background.

I need a runnning stopwatch (the time appears updated each second in the view) and some alarm messages in defined points in time.

The code for the stopwatch is as below:

        this.timer = window.setInterval(function(){
            instance.runtime += Stopwatch.INCREMENT;
            instance.doDisplay();
        }, Stopwatch.INCREMENT);

I'm aware of native solutions, but would like to stick with a JavaScript solution for the sake of cross-platform patibility.

My stopwatch script runs flawlessly in the background on Android (counting up the time), but iOS 4.3.2 seems to pause the script. On iOS the stopwatch stops at the time where the application was sent to background.

I need a runnning stopwatch (the time appears updated each second in the view) and some alarm messages in defined points in time.

The code for the stopwatch is as below:

        this.timer = window.setInterval(function(){
            instance.runtime += Stopwatch.INCREMENT;
            instance.doDisplay();
        }, Stopwatch.INCREMENT);

I'm aware of native solutions, but would like to stick with a JavaScript solution for the sake of cross-platform patibility.

• javascript
• iphone
• ios
• ios4
• cordova

Share Improve this question Follow asked May 4, 2011 at 22:08 Michael SchmidtMichael Schmidt 3,52155 gold badges3535 silver badges3939 bronze badges 2

• Hey I've been searching all over for detecting that an app is running in the background. Can you give me a remendation? – xdumaine Commented Jan 26, 2012 at 14:53
• Does it work accurately on Android, I've tried making code that runs every 5 seconds, it works in background, but not in 5 seconds fixed interval, I think this is because the CPU sleeps, so Did you made it accurate ? How ? – Pola Edward Commented Jan 19, 2014 at 18:58

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1 Answer 1

Sorted by: Reset to default 6

Since setIntervals don't work in the background I'd use a recursive setTimeout instead.
Which means you can't keep track of time with a +=, so you'll need to use a (new Date).getTime(); or Date.now() instead.

this.timer = function myTimer () {
  instance.currentTime = (new Date).getTime();
  instance.doDisplay();
  setTimeout( myTimer, Stopwatch.INCREMENT ); 
}

If the setTimeout doesn't e back to life when the app does it should be simpler to restart.