FB birthday split helper in ES6

bsplit.js

const bsplit = (birthday) => {
  if ( typeof birthday === 'string' ) {
    const data = birthday.split('/')
    let birthdayObj = { day: null, month: null, year: null }

    switch (data.length) {
      case 1:
        birthdayObj.year  = Number( data[0] )
        break
      case 2:
        birthdayObj.day   = Number( data[1] )
        birthdayObj.month = Number( data[0] )
        break
      case 3:
      default:
        birthdayObj.day   = Number( data[1] )
        birthdayObj.month = Number( data[0] )
        birthdayObj.year  = Number( data[2] )
        break
    }
    return birthdayObj
  }
  return birthday
}