BFE.dev 해답 레코드 #23.sum 설치()

문제.

const sum1 = sum(1)
sum1(2) == 3 // true
sum1(3) == 4 // true
sum(1)(2)(3) == 6 // true
sum(5)(-1)(2) == 6 

분석하다.

Let's code

function sum(num, currentSum = 0) {
  const newCurrentSum = num + currentSum
  
  const func = function(arg) {
    return sum(arg, num + currentSum)
  }

  return func
}

function sum(num, currentSum = 0) {
  const newCurrentSum = num + currentSum
  
  const func = function(arg) {
    return sum(arg, num + currentSum)
  }
  
  func.valueOf = () => newCurrentSum
  // below also works
  // func.toString = () => newCurrentSum.toString()
  
  return func
}

통과!