.
.
.
let numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];

// sum: Imperative solution
function imperativeSum(elements) {
  let total = 0;
  elements.forEach(function(n) {
    total += n;
  });
  return total;
}
console.log(imperativeSum(numbers));

// sum: Functional solution
function functionalSum(elements) {
  return elements.reduce((total, n) => { return total += n; });
}
console.log(functionalSum(numbers));