/**
 * @param {string} s
 * @return {number}
 */

var romanToInt = function(s) {
  let numerals = {};
  numerals['M'] = 1000;
  numerals['D'] = 500;
  numerals['C'] = 100;
  numerals['L'] = 50;
  numerals['X'] = 10;
  numerals['V'] = 5;
  numerals['I'] = 1;
  
  let number = 0;
  
  for (let i = 0; i < s.length; ++i){
    let inRange = (i+1 < s.length);
    if (numerals[s.charAt(i+1)] > numerals[s.charAt(i)]){
      number -= numerals[s.charAt(i)];
    } else {
      number += numerals[s.charAt(i)];
    }
  }
  
  return number;
};