isLeapYear

Signature

isLeapYear(value: string): boolean

Return true when the given PlainDate falls in a leap year.

• A leap year is divisible by 4, except for century years which must be divisible by 400.
• Returns false for invalid input strings, including every shape isValidDate rejects: a date-time, zoned, basic-format or leap-second string, or a non-ISO calendar annotation. The annotations Temporal ignores are accepted ("2024-06-15[u-ca=iso8601]" → true).
• Compatibility: earlier releases read those shapes loosely ("2024-03-15T10:00" → true). Pass the date part alone, or use Temporal.PlainDate.from(value).inLeapYear.

Parameters

Parameter	Type	Description
value	string	ISO PlainDate string

Returns

boolean indicating whether the date is in a leap year

Examples

import { isLeapYear } from "@northguild/gmt/plain/validate";

isLeapYear("2024-03-15") // true

value

output

 

Source

plain/validate/isLeapYear.ts