sum.js

const list = [2, 3, 6]

const sum1 = (...args) => {
  return args.reduce((a, b) => a + b)
}

const sum2 = (...args) => {
  let acc = 0
  for (let v of args) {
    acc += v
  }
  return acc
}

const sum3 = (...args) => {
  let acc = 0
  args.forEach(v => {
    acc += v
  })
  return acc
}
const sum4 = (...args) => {
  let acc = 0
  for (let i = args.length; i > 0; i -= 1) {
    acc += args[i]
  }

  return acc
}

const sum4 = (...args) => {
  let acc = 0
  for (let i = 0; i < args.length; i += 1) {
    acc += args[i]
  }

  return acc
}

const sum5 = (...args) => {
  let acc = 0, count = args.length - 1
  while (count > 0) {
    acc += args[count]
    count -= 1
  }
}