Firebase Multipath updates

var ref = new Firebase("https://<YOUR-FIREBASE-APP>.firebaseio.com");

// Generate a new push ID for the new post

var newPostRef = ref.child("posts").push();

var newPostKey = newPostRef.key();

// Create the data we want to update

var updatedUserData = {};

updatedUserData["user/posts/" + newPostKey] = true;

updatedUserData["posts/" + newPostKey] = {

  title: "New Post",

  content: "Here is my new post!"

};

// Do a deep-path update

ref.update(updatedUserData, function(error) {

  if (error) {

    console.log("Error updating data:", error);

  }

});

references:

https://firebase.googleblog.com/2015/09/introducing-multi-location-updates-and_86.html