largest_of_four.js

function largestOfFour(arr) {
  
  for (i=arr.length-1; i>=0; i--){
  	arr[i] = Math.max.apply(null, arr[i]); // I was thinking on doing it with max and reduce buy this looks cleaner
    // Using ES6's spread operator:   arr[i] = Math.max(...arr[i]);
  }
  return arr;
}

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