LeetCode > 1071. Greatest Common Divisor of Strings (JavaScript solution)

leetcode-1071

/**
 * Greatest Common Divisor of Strings
 *
 * @param {String} str1
 *   String of characters.
 *
 * @param {String} str2
 *  String of characters.
 *
 * @return {String}
 *
 * @see https://leetcode.com/problems/greatest-common-divisor-of-strings/description/?envType=study-plan-v2&envId=leetcode-75
 */
const gcdOfStrings = function(str1, str2) {
  const regex = new RegExp(`${str2}(?=${str2})?`, 'g');

  return str1.match(regex) && (str1.replace(regex, '') || str2) || '';
};

gcdOfStrings('ABCABC', 'ABC');  // ABC
gcdOfStrings('ABABAB', 'ABAB'); // AB
gcdOfStrings('LEET', 'CODE');   //

Runtime benchmark with jsPerf