TemporalDateUtils.ts

import { Temporal } from 'temporal'

const TemporalDateUtils = ( datelike: string | Date ) => {
    const date = typeof datelike === 'string' ? new Date( datelike ) : datelike
    const datelikeString = typeof datelike === 'string' ? datelike : date.toISOString()

    const instant = Temporal.Instant.from( date.toISOString() )
    const plainDateString = instant.toString().split( 'T' )[ 0 ]
    const timeIncluded = /T\d+/.test( datelikeString )

    const toPlainDate = () => Temporal.PlainDate.from( plainDateString )
    const toPlainDateTime = () => Temporal.PlainDateTime.from(
        timeIncluded
            ? instant.toString().replaceAll( 'Z', '' )
            : toPlainDate()
    )

    return {
        toPlainDate,
        toPlainDateTime,
    }
}