Query your Backbone.Collections with the MongoDB API
You can run mongo queries on your Backbone.Collections, even in your clientside code. Queries run synchronously on a completely in memory implementation of mongo.
var people = new Backbone.Mongo();
// Use any mongo query you like
var highScorers = people.find({ score: { $gt: 50 }}).fetch();
var obama = people.find({ name: "Barack" }).fetch();
// Inserts and updates work as well
people.insert({ name: "Claire" });
people.update({ name: "Alex" }, { $inc: { score: 10 } });