isValidDateInterval

Signature

isValidDateInterval(start: string, end: string): boolean

Return true if start and end form a valid date interval — both parseable as ISO PlainDate strings and start <= end.

• Both inputs must be ISO 8601 date strings (e.g. "2024-01-01").
• Equal start === end is valid.
• Invalid input, malformed strings, or leap-second strings return false.
• Accepts RFC 9557 calendar-annotated PlainDate strings — E5 (issue #78). Ordering is calendar-independent, so start/end may carry different or no calendar tags (D4).
• Compatibility: since 1.16.0 calendar strings are RFC 9557 (ISO digits, [u-ca=<id>], canonical calendar ids); see isValidCalendarDate.

Parameters

Parameter	Type	Description
start	string	ISO 8601 date string (interval start), optionally calendar-annotated
end	string	ISO 8601 date string (interval end), optionally calendar-annotated

Returns

true if start and end form a valid date interval, or false on invalid input

Examples

import { isValidDateInterval } from "@northguild/gmt/plain/interval";

isValidDateInterval("2024-01-01", "2024-12-31") // true

startend

output

 

Source

plain/interval/validate/isValidDateInterval.ts