Return biggest sum of element in subarray

gistfile1.txt

function largestOfFour(arr) {
var summs = [];
var index = 0;
  for(var i = 0; i < arr.length; i++) {
	summs.push(arr[i].reduce(function(prev, current, index) {
		return prev + current;
    }));
  }
  for(var j = 0; j < summs.length; j++) {
    index = j !== 0 ? summs[j] > summs[j-1] ? j : summs[0] : summs[j];
	
  }
  return arr[index];
}

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