JSX, a year in

A component like this would be rejected in code review for having both a presentation and data concern:

// CommentList.js
import React from "react";

class CommentList extends React.Component {
  constructor() {
    super();
    this.state = { comments: [] }
  }
  
  componentDidMount() {
    fetch("/my-comments.json")
      .then(res => res.json())
      .then(comments => this.setState({ comments }))
  }
  
  render() {
    return (
      <ul>
        {this.state.comments.map(({ body, author }) =>
          <li>{body}-{author}</li>
        )}
      </ul>
    );
  }
}

It would then be split into two components. The first is like a traditional template, concerned only with presentation, and the second is tasked with fetching data and rendering the related view component.

// CommentList.js
import React from "react";

const Commentlist = comments => (
  <ul>
    {comments.map(({ body, author }) =>
      <li>{body}-{author}</li>
    )}
  </ul>
)

// CommentListContainer.js
import React from "react";
import CommentList from "./CommentList";

class CommentListContainer extends React.Component {
  constructor() {
    super();
    this.state = { comments: [] }
  }
  
  componentDidMount() {
    fetch("/my-comments.json")
      .then(res => res.json())
      .then(comments => this.setState({ comments }))
  }
  
  render() {
    return <CommentList comments={this.state.comments} />;
  }
}

In the updated example, CommentListContainer could shed JSX pretty simply.

  render() {
    return React.createElement(CommentList, { comments: this.state.comments });
  }

Additionally, a Higher-order Component or component with Render Props could help in making container components and stateless components more composeable

Junglecrew/on-jsx.markdown