Uncaught TypeError: Cannot read property 'map' of undefined

I am not sure if its is Babel related error as I am new to it. Warning: Failed propType: Required prop players was not specified in Application. Uncaught TypeError: Cannot read property 'map' of undefined at Application (eval at transform.run (babel-browser.min.js:4), <anonymous>:59:20) at ReactCompositeComponentWrapper._constructComponentWithoutOwner (react.js:5720) at ReactCompositeComponentWrapper._constructComponent (react.js:5706) at ReactCompositeComponentWrapper.mountComponent (react.js:5629) at ReactCompositeComponentWrapper.wrapper [as mountComponent] (react.js:12513) at Object.mountComponent (react.js:13175) at ReactCompositeComponentWrapper.performInitialMount (react.js:5767) at ReactCompositeComponentWrapper.mountComponent (react.js:5692) at ReactCompositeComponentWrapper.wrapper [as mountComponent] (react.js:12513) at Object.mountComponent (react.js:13175)

Here is code: var PLAYERS =[ { name: "Theodare", score: 32, }, { name: "Alvin", score: 35, }, { name: "Lily", score: 38, } ];

function Header(props){ return ( <div className = "header"> <h1>{props.title}</h1> </div> ); } Header.propTypes = { title: React.PropTypes.string.isRequired, };

function Player(props){ return ( <div className ="player"> <div className ="player-name"> {props.name} </div> <div className ="player-score"> {props.score} </div> </div> ); } Player.propTypes = { name: React.PropTypes.string.isRequired, score: React.PropTypes.number.isRequired, };

function Application(props){ return ( <div className = "scoreboard"> <Header title={props.title} /> <div className="players"> {props.players.map(function(player) { return <Player name={player.name} score={player.score} /> })}

</div> </div> ); } Application.propTypes = { title: React.PropTypes.string, players: React.PropTypes.arrayOf(React.PropTypes.shape({ name: React.PropTypes.string.isRequired, score: React.PropTypes.number.isRequired, })).isRequired, }; Application.defaultProps = { title: "scoreboard", };

ReactDOM.render(<Application />, document.getElementById('container'));