Millisecond to Human Readable time converter

msToTime.js

function msToTime(duration) {
    const portions = [];
      const msInDay = 1000 * 60 * 60 * 24;
    const days = Math.trunc(duration / msInDay);
    if (days > 0) {
      portions.push(days + 'd');
      duration = duration - (days * msInDay);
    }
  
    const msInHour = 1000 * 60 * 60;
    const hours = Math.trunc(duration / msInHour);
    if (hours > 0) {
      portions.push(hours + 'h');
      duration = duration - (hours * msInHour);
    }
  
    const msInMinute = 1000 * 60;
    const minutes = Math.trunc(duration / msInMinute);
    if (minutes > 0) {
      portions.push(minutes + 'm');
      duration = duration - (minutes * msInMinute);
    }
  
    const seconds = Math.trunc(duration / 1000);
    if (seconds > 0) {
      portions.push(seconds + 's');
    }
  
    return portions.join(' ');
  }

If you want a shorter string, just do return portions[0]