Sum of Three Arrays

sumOfArray.js

var a = [1,2,3,1,1];
var b = [4,5,6,1];
var c = [1,1,1];

function sumArray(a,b,c) {
  const max = Math.max(a.length, b.length, c.length);
  const sumList = [];
  
  for(let i = 0; i < max; i++) {
    sumList.push((a[i] || 0) + (b[i] || 0) + (c[i] || 0));
  }

  return sumList;
}

sumArray(a,b,c); // [6,8,10,2,1]