i have a database which stores the location of users and i want top 20 results nearset to me how to do that in firebase code example

Example: how to push multiple data to different parents in a single request in firebase

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);
  }
});