var dateFns = require ( 'date-fns' ) ; var format = dateFns . format ; var eo = require ( 'date-fns/locale/eo' ) ; var result = format ( new Date ( 2017 , 0 , 25 , 21 , 28 , 15 ) , 'eeee, dd MMMM HH:mm:ss' , { locale : eo } ) ; console . log ( result === 'merkredo, 25 januaro 21:28:15' ) ;