how to change the firebase password code example

Example 1: how to change user password firebase

var user = firebase.auth().currentUser;
var newPassword = getASecureRandomPassword();

user.updatePassword(newPassword).then(function() {
  // Update successful.
}).catch(function(error) {
  // An error happened.
});

Example 2: google auth.onstatechange

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