Allow custom parse function for two digit years

[sbrunecker]

Current Behavior

dayjs parses a two digit year as 19xx if the value is below 68, otherwise as 20xx.

Proposal

A possibility to configure this behavior would be nice. As a use case, we need to parse a two digit year as 19xx if the input is greater than the current year, otherwise as 20xx.

In moment this can be configured, e.g.:

moment.parseTwoDigitYear = function(yearString) {
    return parseInt(yearString) + 2000;
}

[iamkun]

maybe we can support this via a plugin

[sbrunecker]

Would it be an idea to include it as a plugin option to the existing customParseFormat? So it could be configured like so:

dayjs.extend(customParseFormat, {
    twoDigitYearParseFn: yearString => (+yearString) + ((+yearString) > (+dayjs().format('YY')) ? 1900 : 2000)
  })

[iamkun]

fixed in #1421

[maurer2]

Hello, I noticed that in recent versions of dayjs versions, the pivot year seems to be different than the value mentioned above.
The default pivot year now seems to be 1950, instead of 1968 e.g.

dayjs('12/31/49').format() -> 2049-12-31T00:00:00+00:00
dayjs('01/01/50').format() -> 1950-01-01T00:00:00+00:00

Cheers