数字和，更清晰的JS版本

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

const numbers = [1, 2, 3, 4, 5];
const result = sum(numbers);
console.log(result); // 输出15

function sum(numbers) {
  return numbers.reduce((total, current) => total + current, 0);
}

const numbers = [1, 2, 3, 4, 5];
const result = sum(numbers);
console.log(result); // 输出15