JSFiddle - React, Tailwind, and code Playground

JavaScript

function largestOfFour(arr) {
  return arr.map(function (el) {
      return Math.max.apply(null, el);
  });
};

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