Truncate

The Truncate method operates on TIME as an absolute duration since the zero time; it does not operate on the presentation form of the time. If DURATION is a multiple of one hour, Truncate may return a time with a non-zero minute, depending on the time zone.

{{ $t := time.AsTime "2023-01-27T23:44:58-08:00" }}
{{ $d := time.ParseDuration "1h" }}

{{ ($t.Truncate $d).Format "2006-01-02T15:04:05-00:00" }} → 2023-01-27T23:00:00-00:00