Date.prototype.toLocaleTimeString()

new Date().toLocaleTimeString([], {
        hour: "2-digit",
        minute: "2-digit",
        hour12: false,
      });

// "19:18"

new Date().toLocaleDateString("fr", 
  {day: "numeric", month: 'long', year: "numeric"}
);

// "21 septembre 2021"