var PeopleComponent = React.createClass({
    componentDidMount: function() {
        this.props.person.on("change", this._onChange);
    },
    getInitialState: function() {
        return {
            person: this.props.person,

            // trigger async call
            friends: this.props.person.getValue("friends")
        }
    },
    _onChange: function() {
        this.setState(this.getInitialState());
    },
    render: function() {
        <ul> {this.state.friends.map(function(friend) {
            return <li> { friend.name } </li>
        })} </ul>
    };
});