posts.js

const PostList = ({posts}) => (
  posts.map(post => <Post post={post} />)
)


class PostPage extends Component {
  state = {
    posts: []
  }

  componentDidMount() {
    fetchPost().then(posts => this.setState({posts}))
  }

  render() {
    return <PostList posts={this.state.posts}>
  }
}