title: Firebase NodeJS Authentication
body: <p>I have built a fairly basic ExpressJS app and am using Firebase for authentication. When the app loads it checks to see if a user is logged in and if not shows the login screen. The user then enters an email and password and this does a POST to my express ass and logs in the user like so:</p>
  
  <pre><code>app.post('/login-user', function(req, res) {
   firebase.auth().signInWithEmailAndPassword(req.body.email1, req.body.password1).then(function(authData){
     res.redirect('/')
   }).catch(function(error) {
     console.log('mainError', error)
     console.log('error', error.code);
     console.log('message', error.message);
   });
  });
  </code></pre>
  
  <p>This works absolutely fine and the user is logged in and i can access their AuthData. </p>
  
  <p>The issue is this logs the whole app into firebase. If I access the app on another computer it automatically logs in with this user. So basically, only one user can be logged in at one time.</p>
  
  <p>What could I be doing wrong?</p>