JavaScript Library aggregation leaderboard

gistfile1.js

// Scores collection
// [{ user: 'Alice', score: 2 },
// { user: 'Alice', score: 1 },
// { user: 'Bob', score: 4 }]

// Create leaderboard
var agg = new Kinvey.Aggregation();
agg.on('user');
agg.setInitial({ total: 0 });
agg.setReduce(function(doc, out) {
  out.total += doc.score;
});

var collection = new Kinvey.Collection('scores');
collection.aggregate(agg, {
  success: function(response) {
    // response holds:
    // [{ name: 'Alice', total: 3 },
    // {name: 'Bob', total: 4 }]
  },
  error: function(error) {
    // Oops. An error occured.
  }
});