Problem

Given an array of integers, write a function that returns the sum of the elements in the array.
Example input:
[1, 2, 3, 4]
Example output:
10

Solution

// Solution:

function sum(arr) {
  let sum = 0;
  for (let i = 0; i < arr.length; i++) {
    sum += arr[i];
  }
  return sum;
}

// Explanation:
// This solution is optimal because it uses a for loop to iterate through the array and add each element to the sum variable.
// The for loop is the most efficient way to iterate through an array.
// The sum variable is initialized to 0 so that it can be added to.
// The sum variable is returned at the end of the function.