// Created on savesnippets.com · https://savesnippets.com/0SLIZzqXhD8Sis
export function formatDuration(ms: number): string {
  if (ms < 0) return '-' + formatDuration(-ms);
  if (ms < 1000) return `${ms}ms`;

  const units: Array<[string, number]> = [
    ['d', 86_400_000],
    ['h',  3_600_000],
    ['m',     60_000],
    ['s',      1_000],
  ];
  const parts: string[] = [];
  let remaining = ms;
  for (const [label, size] of units) {
    if (remaining >= size) {
      const n     = Math.floor(remaining / size);
      remaining   = remaining % size;
      parts.push(`${n}${label}`);
    }
  }
  return parts.join(' ') || '0s';
}

formatDuration(750);            // '750ms'
formatDuration(75_000);         // '1m 15s'
formatDuration(3_725_000);      // '1h 2m 5s'
formatDuration(90_000_000);     // '1d 1h'