title: TypeError: Cannot read property 'FieldValue' of undefined
body: <pre><code>  19 | event.preventDefault();
    20 | db.collection('todos').add({
    21 |   todo:input,
    22 |   timestamp: firebase.firestore.FieldValue.serverTimestamp()
    23 |  });
    24 | 
    25 | setInput(&quot;&quot;);
  </code></pre>
  <p>Whenever I try to run this code, it shows me type error. So that I cant able to push the data to firebase</p>