const millisToMinutesAndSeconds = (millis) => {
    var minutes = Math.floor(millis / 60000);
    var seconds = ((millis % 60000) / 1000).toFixed(0);
    //ES6 interpolated literals/template literals 
      //If seconds is less than 10 put a zero in front.
    return `${minutes}:${(seconds < 10 ? "0" : "")}${seconds}`;
}