title: angularfire2 transactions and batch writes in firestore
body: <p>How can I do batch writes/run transactions with firestore in an angular2 app?</p>
  
  <p><a href="https://firebase.google.com/docs/firestore/manage-data/transactions" rel="noreferrer">https://firebase.google.com/docs/firestore/manage-data/transactions</a></p>
  
  <p>If it's possible, how can I convert the JS code to TS code in an angular2 app.</p>