code: function getPattern(word) {
  	return MARK_GROUPS.reduce((pattern, group) => {
  		// Strip the last character which is a character without diacritic mark
  		const groupPattern = `[${group.substring(0, group.length - 1)}]`;
  		return pattern.replace(new RegExp(groupPattern, 'ig'), `[${group}]`);
  	}, word);
  }
docs: Replace all diacritics with RegExp patterns that match that character with or without a diacritic mark:
  décor → d[éèêëe]cor
  
  @param {string} word
  @return {string}