input.js

const REGEXP_KOREAN_ALPHABET = '[a-zA-Z가-힣ㄱ-ㅎㅏ-ㅣ]{1,}'
const REGEXP_KOREAN_ALPHABET_NUMBER = '[a-zA-Z가-힣ㄱ-ㅎㅏ-ㅣ0-9 _]{1,}'
const REGEXP_KOREAN_ALPHABET_WHITESPACE = '[a-zA-Z가-힣ㄱ-ㅎㅏ-ㅣ ]{1,}'
const REGEXP_NUMBER = '[0-9]{0,}'

const REGEXP = {
  // 한글, 영문, 숫자, 공백허용, 특수기호 불가능
  KOREAN_ALPHABET_NUMBER_WHITESPACE: /[가-힣ㄱ-ㅎㅏ-ㅣa-zA-Z0-9\s]/g,
  // 한글, 영문, 숫자, 공백허용, 일부 특수기호 허용 (즉, 이모지 불가능)
  ALL_AND_LIMITED_SPECIAL_CHARACTERS: /[가-힣ㄱ-ㅎㅏ-ㅣa-zA-Z0-9\s`₩~!@#$%^&*()_+\-=[\]{}<>,.?/|\\'":;]/g,
  // 숫자만 허용
  NUMBER: /[0-9]/g,
};

date.js

const [year, month, date] = birthDateStr
  .replace(/(\d{4})(\d{2})(\d{2})/, '$1-$2-$3')
  .split('-')

'2018.02.14'
  .replace(/\d{4}.(\d{2}).(\d{2})/, '$1/$2')
  .replace(/^0/, '') // 2/14
'2018.12.14'
  .replace(/\d{4}.(\d{2}).(\d{2})/, '$1/$2')
  .replace(/^0/, '') // 12/14

url.js

const URL_REGEXP = /^(http:\/\/www\.|https:\/\/www\.|http:\/\/|https:\/\/)?[a-z0-9]+([-.]{1}[a-z0-9]+)*\.[a-z]{2,5}(:[0-9]{1,5})?(\/.*)?$/

const urlToAnchor = (url) => {
  return url.replace(URL_REGEXP, '<a href="$&">$&</a>')
}

special-char.js

const escapeSpecialChar = str => str.replace(
  /[.*+?^${}()|[\]\\]/g,
  '\\$&'
);