For more information visit: https://leetcode.com/problems/roman-to-integer/

romanToInt.js

const SYMBOLS = {
  "I": 1,
  "V": 5,
  "X": 10,
  "L": 50,
  "C": 100,
  "D": 500,
  "M": 1000
}

function romanToInt(s: string): number {
  let total = 0
  for(let i = 0; i < s.length; i++){
    const symbol = s[i]
    let value = SYMBOLS[symbol]
    const nextSymbol = s[i+1]
      
    if(!!nextSymbol 
      && (
        (symbol === "I" && (nextSymbol === "V" || nextSymbol === "X")) 
        || (symbol === "X" && (nextSymbol === "L" || nextSymbol === "C")) 
        || (symbol === "C" && (nextSymbol === "D" || nextSymbol === "M"))
      )
    )
     value *= -1
    
      
    
    total += value
  }
  
  return total
};