title: Check if data equals something on Firebase
body: <p>When the user registers, I send this to the database, along with the users information: <code>firstLogin: "false"</code></p>
  
  <p>When the user signs in, I want to check if it's their first time doing that, so I want to check if the firstLogin equals "false".</p>
  
  <p>I tried doing it this way but it's not working.</p>
  
  <pre><code>firebase.auth().signInWithEmailAndPassword(email, password).then( () =&gt;{
  let user = firebase.auth().currentUser;
  if (user.firstLogin === "false"){
      firebase.database().ref('users/' + user.uid).update({
          firstLogin: "true"
      });
  }
  </code></pre>