Script to parse roman numerals to equivalent integer

RomanNumerals.ts

/**
 * Decodes a Roman numeral to a number.
 *
 * @param {string} roman - The Roman numeral to decode.
 * @returns {number} The decoded Roman numeral.
*/

const numerals: Record<string, number> = {
  'I': 1,
  'V': 5,
  'X': 10,
  'L': 50,
  'C': 100,
  'D': 500,
  'M': 1000,
}

const evaluateNumbersList = (list: number[]): number => {
  const [first, second] = list.slice(0, 2)
  
  if(!first)
    return 0;
  
  if(!second)
    return first;
  
  if(first < second)
    return (second - first) + evaluateNumbersList(list.slice(2));
  
  return first + evaluateNumbersList([second, ...list.slice(2)]);
};

const decode = (roman: string): number => {
  const parsedValues = roman.split('').map(char => numerals[char]);
  
  return evaluateNumbersList(parsedValues);
};

export { decode };