Return largest numbers in arrays

function largestOfFour (arr) {
  var newArr = []

  for (var i = 0; i < arr.length; i++) {
    newArr.push(arr[i].sort((a, b) => a - b).pop())
  }

  return newArr
}

largestOfFour([[4, 5, 1, 3], [13, 27, 18, 26], [32, 35, 37, 39], [1000, 1001, 857, 1]])