AddTime

AddTime is a common name for a function in date and time manipulation libraries that returns a new timestamp by adding a specified duration to a base date. It is not a standard language feature but appears in many frameworks and utilities to facilitate calendar arithmetic and time calculations.

Typical signature: addTime(date, amount, unit) with unit commonly representing seconds, minutes, hours, days, weeks, months, or years. The function usually returns a new date object, and the input date is not mutated. Some libraries also support relative durations expressed as strings, such as "2 days," instead of separate amount and unit.

Behavior notes: for fixed-length units (seconds to days), the result is straightforward. For calendar units (months, years), the result may depend on the original day of the month; many implementations preserve the day when possible, or adjust to the last valid day of the target month. Time zone handling and daylight saving time can also influence the final result, depending on the date library’s conventions.

Examples: adding one month to January 31, 2020 often yields February 29, 2020 in a leap year, while adding 24 hours to a date yields the same effect as adding one day in most cases. Negative amounts perform subtraction. Exact syntax and behavior vary by library and language.

See also: date arithmetic, time duration, time zones, daylight saving time.