eloquent javascript The sum of a range

eloquentjavascript-The sum of a range.js

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

function range(start, end, step = 1) {
  const rangeArray = []
  const direction = end > start
  
  for(let i = start; (direction ? (i <= end) : (i >= end)); i += step) {
    rangeArray.push(i)
  }
  
  return rangeArray
}



console.log(range(1, 10))
console.log(range(2, 5))
console.log(range(1, 10, 2))
console.log(range(5, 2, -1))
console.log(sum(range(1, 2)))
console.log(sum(range(10, -20, -1)))