inSeconds property
The number of whole seconds spanned by this Duration.
The returned value can be greater than 59. For example, a duration of three minutes and 12 seconds has 192 seconds.
const duration = Duration(minutes: 3, seconds: 12);
print(duration.inSeconds); // 192 = 3 * 60 + 12
A negative duration has a negative number of whole seconds,
so that (-duration).inSeconds = -(duration.inSeconds).
Implementation
int get inSeconds => inMicroseconds ~/ Duration.microsecondsPerSecond;