firebase

gistfile1.js

//creating a firebase object 
var datafire = new Firebase('https://purchases.firebaseio.com');

//a listener that watches the firebase server for changes to our object and executes a callback
//I guess we're going to need to generate one when a user logs in so they can watch only their object for changes
datafire.on('value', function(snapshot){
  var firedata = snapshot.val();
  console.log(firedata);
});

//pushing data to our firebase object
datafire.set({"UID":"soAndSo"}); //sample data


//api calls we're going to have to service
getConnections(callback); //--> [{uid: "", name: ""}, {uid: "", name: ""}, {uid: "", name: ""}] OR false
getName(uid, callback); //--> name OR false
postTransaction(obj, uid, callback); //--> uid is optional, if present mutates obj to contain logged in user's uid in "to" attribute inserts obj into user UID's transaction array, otherwise inserts unmutated object into authenticated user's transaction array. 

I believe this is what we're looking for:
"Child Changed

This event will be triggered when the data stored in a child (or any of its descendants) changes. Note that a single child_changed event may represent multiple changes to the child. The DataSnapshot passed to the callback will contain the new child contents. For ordering purposes, the callback is also passed a second argument which is a string containing the name of the previous sibling child by priority order (or null if it is the first child)."

firebaseRef.on('child_changed', function(childSnapshot, prevChildName) {
// code to handle child data changes.
});