React-dnd教程 - ES5和ES2015版本都抛出了Game.observe不是一个功能＆＃39;

Question

这里有什么问题？

＆＃39;未捕获的TypeError：（0，_Game.observe）不是函数＆＃39;

  

Game.jsx

export function observe(receive) {
    setInterval(() => receive([
        Math.floor(Math.random() * 8),
        Math.floor(Math.random() * 8)
    ]), 500);
};

  

index.jsx

import React from 'react';
import ReactDOM from 'react-dom';
import Board from './Board';
import { observe } from './Game';

const rootEl = document.getElementById('root');

observe(knightPosition => 
    ReactDOM.render(
        <Board knightPosition={knightPosition} />,
        rootEl
    )
);