Statechart.js

var machine = _.extend({

    // slots
    count: 1,
    done: function() {},

    // logic
    initialState: 'Init',
    states: {

        Init: {
            data: {
                guard: function(data) {
                    return --this.count == 0;
                },
                target: 'Done'
            },
            error: {
                guard: function(err) {
                    console.log(err);
                    return --this.count == 0;
                },
                target: 'Done'
            }
        },
        Done: {
            entry: function() {
               this.done();
            }
        }
    }

}, Statechart);

    
function dispatch(err, doc) {
    if (err)
        return machine.dispatch('error', err);
    machine.dispatch('data', doc);
}

machine.count = 3;
machine.done = function() {
    console.log('All documents received.');
};

machine.run();

db.get('myID1', dispatch);
db.get('myID2', dispatch);
db.get('myID3', dispatch);