Check deep equality in javascript

equals.js

const equals = (obj1, obj2) => {
  const sortKeys = (obj) =>
    (obj && typeof obj === 'object')
      ? Object.keys(obj)
          .sort((a, b) => a < b)
          .reduce((newObj, key) => {
            newObj[key] = sortKeys(obj[key])
            return newObj
          }, {})
      : obj

  const [ one, two ] =
    [ obj1, obj2 ]
      .map(sortKeys)
      .map(JSON.stringify)

  return one === two
}