negateDuration

Signature

negateDuration(value: string): string

import { negateDuration } from "@northguild/gmt/duration/calculate";

Flip the sign of an ISO 8601 duration string.

• Uses Temporal.Duration.from and .negated, then .toString() to re-emit.
• Negating is a pure sign flip on every component, so it never needs relativeTo — calendar-unit durations round-trip through it fine, unlike addDuration/durationAs.
• A zero-length duration has no sign to flip and comes back as “PT0S”, the canonical spelling Temporal emits for every zero duration (so “P0D” also renders “PT0S”).
• Returns “” when value is not a valid ISO 8601 duration string.

Parameters

Parameter	Type	Description
value	string	ISO 8601 duration string

Returns

ISO 8601 duration string with the opposite sign, or “” on invalid input

Examples

negateDuration("P1DT2H") // "-P1DT2H"
negateDuration("-P1DT2H") // "P1DT2H"
negateDuration("P1Y2M") // "-P1Y2M" (no relativeTo needed)
negateDuration("PT0S") // "PT0S"
negateDuration("not a duration") // ""

Source

duration/calculate/negateDuration.ts