```ts
/** The quickest completed lap of a session. */
export function lapBest(laps: number[]): number {
  if (laps.length === 0) {
    return 0;
  }
  let best = Number.MAX_VALUE;
  for (const lap of laps) {
    if (lap > 0 && lap < best) {
      best = lap;
    }
  }
  return best;
}
```