gistfile1.txt

// Observer the body tag of all html files. use validateLogIn function to verfy the login activity

function validateLogIn () {
  const uName = document.getElementById('uName')
  const signOut = document.getElementById('signout')
  signOut.addEventListener('click', () => {
    sessionStorage.clear('login')
    window.location.href = '../sign-in.html'
  })

  const sessionLogin = sessionStorage.getItem('login')

  if (!sessionLogin) {
    alert('You must sign in')
    window.location.href = '../sign-in.html'
    return
  }

  const localUser = localStorage.getItem('user')
  const user = JSON.parse(localUser)

  uName.innerHTML = user.username
}

// Add event listener to every sign out button in the header as asked in the problem statement.