var romanToInt = function (s) {

  const converter = value => {

    switch (value) {

      case 'I':

        return 1

      case 'IV':

        return 4

      case 'V':

        return 5

      case 'IX':

        return 9

      case 'X':

        return 10

      case 'XL':

        return 40

      case 'L':

        return 50

      case 'XC':

        return 90

      case 'C':

        return 100

      case 'CD':

        return 400

      case 'D':

        return 500

      case 'CM':

        return 900

      case 'M':

        return 1000

      default:

        break

    }

  }

  let sum = 0

  const arrRoman = s.split('')

​

  const checkArr = [...arrRoman]

​

  for (let index in arrRoman) {

    if (+index + 1 < checkArr.length) {

      if (

        (arrRoman[index] === 'I' && arrRoman[+index + 1] === 'V') ||

        (arrRoman[index] === 'I' && arrRoman[+index + 1] === 'X') ||

        (arrRoman[index] === 'X' && arrRoman[+index + 1] === 'L') ||

        (arrRoman[index] === 'X' && arrRoman[+index + 1] === 'C') ||

        (arrRoman[index] === 'C' && arrRoman[+index + 1] === 'D') ||

        (arrRoman[index] === 'C' && arrRoman[+index + 1] === 'M')

      ) {

        arrRoman.splice(index, 2, arrRoman[index] + arrRoman[+index + 1])

      }

    }

  }

​

  for (let romNum of arrRoman) {

    sum += converter(romNum)

  }

  return sum

}

​

var romanToInt = function(str) {

    const code = {

        'I': 1, 

        'V': 5, 

        'X': 10, 

        'L': 50, 

        'C': 100, 

        'D': 500, 

        'M': 1000

    }

    let total = 0;

    for (let i = 0; i < str.length; i++) {

        let current = code[str[i]];

        let next = code[str[i + 1]];

        if (current < next) {

            total -= current;

        } else {

            total += current;

        }

    }

    return total;

};

​

​

​

​