问将JSX数据作为JSON从Express后端发送，然后将其作为组件显示在React前端

EN

import React, { Component } from "react";
import "./App.css";

class App extends Component {
  state = { users: [] };

  componentDidMount() {
    fetch("http://localhost:3001/users")
      .then(res => res.json())
      .then(users => this.setState({ users }))
      .catch(error => { });
  }

  render() {
    return <div className="App">
        <h1>Users</h1>
        {this.state.users.map(user => <div key={user.id}>
            {user.username}
          </div>)}
      </div>;
  }
}

export default App;

var express = require("express");
var router = express.Router();

/* GET users listing. */
router.get("/", function(req, res, next) {
  // Comment out this line:
  //res.send('respond with a resource');

  // And insert something like this instead:
  res.json([
    {
      id: 1,
      username: "samsepi0l"
    },
    {
      id: 2,
      username: "D0loresH4ze"
    }
  ]);
});

module.exports = router;