maxDistToClosest.js

const maxDistToClosest = (seats,
  [maxDist, i, j] = [0, 0, 1],
  { length } = seats) => {
  const leftSeatOccupied = () => seats[i] === 1;
  const rightSeatOccupied = () => seats[j] === 1;
  const isEndOfRow = () => (j + 1) === length;
  const distanceToEndOfRow = () => j - i;
  const distanceBetweenSeats = () => Math.ceil(((j - 1) - i) / 2);
  const seatsLeftInRow = () => j < length;
  const checkNextRightSeat = () => j += 1;
  const checkNextGap = () => i = j++;
  const areBetweenOccupiedSeats = () => rightSeatOccupied() && leftSeatOccupied();

  while (seatsLeftInRow()) {
    while (!rightSeatOccupied() && !isEndOfRow()) {
      checkNextRightSeat();
    }

    maxDist = areBetweenOccupiedSeats()
      ? Math.max(maxDist, distanceBetweenSeats())
      : Math.max(maxDist, distanceToEndOfRow())

    checkNextGap();
  }

  return maxDist;
}