Date and time functionality.

localizedFormat(instant, offset) and localizedLongDateString(instant, offset) use the explicit UTC offset supplied to Moment's utcOffset, such as -300 for UTC-05:00 or 330 for UTC+05:30. They do not infer a location or daylight saving. Supply the effective offset for the instant. Moment also accepts offset strings, such as "+00:05", and treats numeric offsets with an absolute value below 16 as hours.

For New York in summer, pass the effective offset -240, rather than the standard-time offset -300. For location-based formatting, resolve an IANA timezone using a timezone-aware library rather than guessing a location from a numeric offset.