this.state.players.map(function(player){...}? Where does players come from if we changed players to initialPlayers?

Hello!

As you see in the video, the Application component receives the initialPlayers prop. Inside the component you can see that the getInitialState method enables to set the initial state value of players (players is a property of the state object) to initialPlayers like this:

getInitialState: function() {
    return {
        players: this.props.initialPlayers
    };
}

Happy coding!

players doesn't need to be defined as a propType because it's not an actual property param of the component.

examples: <Player name={} score={} key={} />, <Counter score={} />

For Application we just want to give it an initial list of players....

So, defined propTypes are things that would be passed in as arguments for the component i.e initalPlayers here and accessible by the PROPS object. this.props.initialPlayers;

<Application initialPlayers={} />

In order to properly change the state of an object or variable we need to access the STATE object for the component.

He is using an object named players as a secondary array to change state with. this.STATE.players. This makes the code a little more readable and understandable.

"Give the application an initial list of players called initialPlayers. The application should be able to make changes to the state of players."

We are just assigning an object named players to state, that name could be whatever we want and we are able to access it from the state object this.state.variableName.

We can then reset the players object with this.setState({ players: this.props.initialPlayers });

Hey Arturo Goicochea you ever find out why it wasn't defined in the proptypes?