Timer.ts

export class Timer {
  static FORMAT = {
    NANOSECOND: 'ns',
    MILLISECOND: 'ms',
  } as const;

  private start = this.now;

  private get now() {
    return process.hrtime.bigint();
  }

  public duration(
    format: (typeof Timer.FORMAT)[keyof typeof Timer.FORMAT],
  ): number {
    const elapsedNanoseconds = Number(this.start - this.now);

    switch (format) {
      case Timer.FORMAT.NANOSECOND:
        return elapsedNanoseconds;
      case Timer.FORMAT.MILLISECOND:
        return Math.round(elapsedNanoseconds / 1000000);
    }
  }
}