largestOfFour

function largestOfFour(arr) {
  var largestNums = []; 
  for (i = 0; i < arr.length; i++){
    arr[i].sort(function(a, b){return a - b;});
    var largestNum = arr[i][arr.length-1];
    largestNums.push(largestNum);
  }
  console.log(largestNums);
  return largestNums;
}

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