title: Firebase auth: Update (not signed in user) password without use 'sendPasswordResetEmail'
body: <p>I know how to update the password of <strong>signed in user</strong> in firebase auth:</p>
  <pre class="lang-js prettyprint-override"><code>var user = firebase.auth().currentUser; //get current connected user
      return user.updatePassword(newPass)
        .then(
          () =&gt; //success
        )
        .catch(error =&gt; this.handleError(error))
    }
  </code></pre>
  <p>But I don't know how to do the same with a <strong>not signed in user</strong>. Perhaps retrieve user auth persistance only with his email with kind like that (but there is no way to do that):</p>
  <pre class="lang-js prettyprint-override"><code>var user = firebase.auth().getUserByEmail(email); //not implmented in auth firebase
  </code></pre>
  <p>PS: I don't want to use the method <em>sendPasswordResetEmail()</em></p>
  <pre class="lang-js prettyprint-override"><code>var auth = firebase.auth();
      return auth.sendPasswordResetEmail(email);
  </code></pre>
  <p>Greatly appreciated help,
  Thanks !</p>