How to calculate time difference?

General
1

Hello;

I would like to calculate time when start 22:00:00 in the database and the end time is 02:30:00. Who has an idea for calculate 22:00:00 to 02:30:00( Total 04:30:00 Hour ) in the node-red?

Thank you.

2

Here is code I have used to figure sunset and sunrise .. perhaps this could help.
hr=msg.payload.sun_phase.sunrise.hour;
min=msg.payload.sun_phase.sunrise.minute;
srise = hr+':'+min;
sriseCalc = new Date();
sriseCalc = execTime(sriseCalc, srise, -15);
hr=msg.payload.sun_phase.sunset.hour;
min=msg.payload.sun_phase.sunset.minute;
sset = hr+':'+min;
ssetCalc = new Date();
ssetCalc = execTime(ssetCalc, sset, 15);
msg.payload = {sunrise : srise, sunset : sset,calcSunrise : sriseCalc.getTime(), calcSunset : ssetCalc.getTime()};
context.global.astroData = {calcSunrise : sriseCalc.getTime(), calcSunset : ssetCalc.getTime()};// context.global.astroData;
return msg;

function execTime (t, target, delay) {
arr = target.split(':');
t.setHours(arr[0]);
t.setMinutes(arr[1]);
t.setMinutes(t.getMinutes() + (delay));
return t;
}

3

As always, don't forget to think about local vs UTC times. If using local, you need to take into account any daylight savings changes.

4

Thank you very much. I will do it.

5

Assuming the times are javascript Date objects then you can just subtract them to get the difference in milliseconds. Simple example:

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