DATE

const timestamp = new Date().getTime();

console.log(timestamp)

let DAY_FORMATTER = new Intl.DateTimeFormat(undefined, { weekday: "long",

month: "long" })

console.log(DAY_FORMATTER.format(timestamp))

DAY_FORMATTER = new Intl.DateTimeFormat(undefined, { dayPeriod: "short"

, weekday: "short", year: "numeric"

, month: "short", day: "numeric" })

console.log(DAY_FORMATTER.format(0))

Les valeurs possibles : 

{
  weekday: 'narrow' | 'short' | 'long',
  era: 'narrow' | 'short' | 'long',
  year: 'numeric' | '2-digit',
  month: 'numeric' | '2-digit' | 'narrow' | 'short' | 'long',
  day: 'numeric' | '2-digit',
  hour: 'numeric' | '2-digit',
  minute: 'numeric' | '2-digit',
  second: 'numeric' | '2-digit',
  timeZoneName: 'short' | 'long',

  // Time zone to express it in
  timeZone: 'Asia/Shanghai',
  // Force 12-hour or 24-hour
  hour12: true | false,
}