const ordinal = require("ordinal")
const { days, months } = require("date-names")

exports.formatDate = function (date, format) {
  return format.replace(/YYYY|M(MMM)?|Do?|dddd/g, (tag) => {
    if (tag == "YYYY") return date.getFullYear()
    if (tag == "M") return date.getMonth()
    if (tag == "MMMM") return months[date.getMonth()]
    if (tag == "D") return date.getDate()
    if (tag == "Do") return ordinal(date.getDate())
    if (tag == "dddd") return days[date.getDay()]
  })
}

const { formatDate } = require("./format-date")

console.log(formatDate(new Date(2017, 9, 13), "dddd the Do"))
// → Friday the 13th