เวลาแบบสัมพันธ์และพหูพจน์

const rtf = new Intl.RelativeTimeFormat("en-US");
console.log(rtf.format(-1, "day")); // "1 day ago"
console.log(rtf.format(2, "hour"));  // "in 2 hours"

const rtf = new Intl.RelativeTimeFormat("en-US");
console.log(rtf.format(-3, "week")); // "3 weeks ago"
console.log(rtf.format(5, "minute")); // "in 5 minutes"

const rtf = new Intl.RelativeTimeFormat("en-US", { numeric: "auto" });
console.log(rtf.format(-1, "day")); // "yesterday"
console.log(rtf.format(0, "day"));  // "today"

console.log(new Intl.RelativeTimeFormat("es").format(-2, "day")); // "hace 2 dias"
console.log(new Intl.RelativeTimeFormat("fr").format(3, "hour")); // "dans 3 heures"

function ago(date) {
  const diff = (date - Date.now()) / 1000;
  const rtf = new Intl.RelativeTimeFormat("en-US", { numeric: "auto" });
  if (Math.abs(diff) < 60) return rtf.format(Math.round(diff), "second");
  if (Math.abs(diff) < 3600) return rtf.format(Math.round(diff / 60), "minute");
  return rtf.format(Math.round(diff / 3600), "hour");
}
console.log(ago(new Date(Date.now() - 90000)));

const pr = new Intl.PluralRules("en-US");
console.log(pr.select(1)); // "one"
console.log(pr.select(2)); // "other"
console.log(pr.select(0)); // "other"

const pr = new Intl.PluralRules("en-US");
const forms = { one: "item", other: "items" };
function label(n) { return n + " " + forms[pr.select(n)]; }
console.log(label(1)); // "1 item"
console.log(label(5)); // "5 items"

const pr = new Intl.PluralRules("pl");
console.log(pr.select(1)); // "one"
console.log(pr.select(3)); // "few"
console.log(pr.select(5)); // "many"

const pr = new Intl.PluralRules("en-US", { type: "ordinal" });
const suffix = { one: "st", two: "nd", few: "rd", other: "th" };
function ordinal(n) { return n + suffix[pr.select(n)]; }
console.log(ordinal(1), ordinal(2), ordinal(3), ordinal(11)); // 1st 2nd 3rd 11th

const nf = new Intl.NumberFormat("en-US");
const pr = new Intl.PluralRules("en-US");
const forms = { one: "file", other: "files" };
function msg(n) { return nf.format(n) + " " + forms[pr.select(n)]; }
console.log(msg(1000)); // "1,000 files"

const lf = new Intl.ListFormat("en-US", { type: "conjunction" });
console.log(lf.format(["red", "green", "blue"])); // "red, green, and blue"