Push and return Firebase

example.js

const ref = new Firebase('<my-firebase-app>/items');
// Create a push reference (no data has been sent to the server, just a generated id)
const childRef = ref.push();
// create an object and with they push-id
const data = { name: 'David': key: childRef.key() };
// save it
childRef.set(data);

// Listen for the update
childRef.on('value', (snap) => console.log(snap.val()));