Object.prototype.toLocaleString()

const date = new Date(Date.UTC(2012, 11, 20, 3, 0, 0));

console.log(date.toLocaleString("ar-EG"));
// : "// :: "

const number = 123456.789;

console.log(number.toLocaleString("de-DE"));
// : "123.456,789"

toLocaleString()

const obj = {
  toString() {
    return "My Object";
  },
};
console.log(obj.toLocaleString()); // "My Object"

const testArray = [4, 7, 10];

const euroPrices = testArray.toLocaleString("fr", {
  style: "currency",
  currency: "EUR",
});
// "4,00 ,7,00 ,10,00 "

const testDate = new Date();
// "Date Fri May 29 2020 18:04:24 GMT+0100 "

const deDate = testDate.toLocaleString("de");
// "29.5.2020, 18:04:24"

const frDate = testDate.toLocaleString("fr");
// "29/05/2020, 18:04:24"

const testNumber = 2901234564;
// "2901234564"

const deNumber = testNumber.toLocaleString("de");
// "2.901.234.564"

const frNumber = testNumber.toLocaleString("fr");
// "2 901 234 564"