helpreact.js

const routes = (
  <Router history={browserHistory}>  
    <Route path="/">
      <Route path="/posts/:id" component={PostPage} />
    </Route>
  </Router>
)

<button onClick={() => browserHistory.push(`/posts/${post.id}`)}></button>

class PostPage extends Component {
  state = { post: null, loading: false, error: null }
  componentWillMount() {
    this.setState({ loading: true });
    axios.get(`http:localhost:3000/api/posts/${this.props.params.id}`)
      .then(
        res => this.setState({ post: res.post, loading: false }),
        err => this.setState({ error: true, loading: false });
      )
  }

  render() {
    if (this.state.loading) { return <h1>Loading...</h1>; }
    else if (!this.state.loading) {
      if (this.state.error) { return <h1>Error...</h1>}
      return (
        <div>
          <h1>{this.state.post.title}</h1>
        </div>
      );
    }
  }
}

router.route('/api/posts/:id', (req, res) => {
  Posts.findById(req.params.id)
    .then(
      post => res.status(201).json({ post, success: true }),
      err => res.status(422).json({ success: false, error: 'No Post find' })
    );
});