connected.js

import { connect } from 'react-redux';

const Score = ({ score }) => (<div className="game-score"> {score} </div>);

const mapStateToProps = (state) => ({ score: state.game.score });
export default connect(mapStateToProps)(Score)

/*******************************/

import { connect } from 'react-redux';

const shoot = () => ({type: 'SHOOT', weapon: 'laser'});

const ShootButton = ({ shoot }) => (
    <button className="game-controls-fire" onClick={ shoot }>
        Fire
    </button>
);

const mapStateToProps = () => ({});
const mapDispatchToProps = (dispatch) => ({ shoot: (e) => dispatch(shoot()) });

export default connect(mapStateToProps, mapDispatchToProps)(ShootButton)