firebase authenticationchanged code example

Example 1: google auth.onstatechange

firebase.auth().onAuthStateChanged(function(user) {  if (user) { 
// User is signed in. 
} 
  else {   
    // No user is signed in.
  }});

Example 2: firebase.auth.currentuser

var user = firebase.auth().currentUser;if (user) {  // User is signed in.} else {  // No user is signed in.}