Javascript Roman à Integer

const values = new Map([
  ['I', 1],
  ['V', 5],
  ['X', 10],
  ['L', 50],
  ['C', 100],
  ['D', 500],
  ['M', 1000],
]);

function romanToInt(string) {
  let result = 0,
    current, previous = 0;
  for (const char of string.split("").reverse()) {
    current = values.get(char);
    if (current >= previous) {
      result += current;
    } else {
      result -= current;
    }
    previous = current;
  }
  return result;
}
Wombat