isBefore method

bool isBefore (DateTime other)

Returns true if this occurs before other.

The comparison is independent of whether the time is in UTC or in the local time zone.

var now = new DateTime.now();
var earlier = now.subtract(const Duration(seconds: 5));
assert(earlier.isBefore(now));
assert(!now.isBefore(now));

// This relation stays the same, even when changing timezones.
assert(earlier.isBefore(now.toUtc()));
assert(earlier.toUtc().isBefore(now));

assert(!now.toUtc().isBefore(now));
assert(!now.isBefore(now.toUtc()));

Implementation 

bool isBefore(DateTime other) {
  return _value < other._value;
}