rails-with-react-posts-4.jsx

// app/javascript/components/Posts.js

...
  renderAllPosts = () => {
    return(
      <ul>
        {this.state.posts.map(post => (
          <li key={post}>{post}</li>
        ))}
      </ul>
    )
  }

  render() {
    return (
      <div>
        {this.renderAllPosts()}
      </div>
    )
  }
...