尝试得到react-router (v4.0.0)和react-hot loader (3.0.0-beta.6)很好地发挥,但在浏览器控制台得到以下错误:

Warning: React.createElement: type is invalid -- expected a string
(for built-in components) or a class/function (for composite
components) but got: undefined. You likely forgot to export your
component from the file it's defined in.

index.js:

import React from 'react';
import ReactDom from 'react-dom';
import routes from './routes.js';
require('jquery');
import 'bootstrap/dist/css/bootstrap.min.css';
import 'bootstrap/dist/js/bootstrap.min.js';
import './css/main.css';

const renderApp = (appRoutes) => {
    ReactDom.render(appRoutes, document.getElementById('root'));
};

renderApp( routes() );

routes.js:

import React from 'react';
import { AppContainer } from 'react-hot-loader';
import { Router, Route, browserHistory, IndexRoute } from 'react-router';
import store from './store/store.js';
import { Provider } from 'react-redux';
import App from './containers/App.jsx';
import Products from './containers/shop/Products.jsx';
import Basket from './containers/shop/Basket.jsx';

const routes = () => (

    <AppContainer>
        <Provider store={store}>
            <Router history={browserHistory}>
                <Route path="/" component={App}>
                    <IndexRoute component={Products} />
                    <Route path="/basket" component={Basket} />
                </Route>
            </Router>
        </Provider>
    </AppContainer>

);

export default routes;

当前回答

在我的例子中,我的组件中有文本组件,当我像这样导入没有花括号的文本时,这就是错误的原因

import Text from '..';  <-wrong

为了修复这个错误,我像这样在花括号内导入Text

import {Text} from '..';  <-right

其他回答

我得到了这个错误,没有一个响应是我的情况下,这可能会帮助一些人谷歌:

我定义了一个错误的Proptype:

ids: PropTypes.array(PropTypes.string)

它应该是:

ids: PropTypes.arrayOf(PropTypes.string)

VSCode和编译错误没有给我一个正确的提示。

您需要了解命名导出和默认导出。我什么时候应该用大括号导入ES6 ?

在我的例子中,我通过改变

import Provider from 'react-redux'

to

import { Provider } from 'react-redux'

在我的例子中,错误发生在试图使用ContextApi时。我错误地使用了:

const MyContext = () => createContext()

但它应该被定义为:

const MyContext = createContext()

我把它贴在这里,以便未来的访客谁被困在这样一个愚蠢的错误将得到帮助,以避免几个小时的头痛,因为这不是由不正确的导入/导出引起的。

对我来说,删除Switch解决了这个问题

import React from "react";
import "./styles.css";
import { Route, BrowserRouter, Routes } from "react-router-dom";
import LoginPage from "./pages/LoginPage";
import HomePage from "./pages/HomePage";

export default function App() {
  return (
    <BrowserRouter>
      <Routes>
        <Route exact path="/" element={<HomePage />} />
        <Route path="/login" element={<LoginPage />} />
      </Routes>
    </BrowserRouter>
  );
}

我已经遇到过这个问题了。我的解决方案是:

在文件配置路由:

const routes = [
    { path: '/', title: '', component: Home },
    { path: '*', title: '', component: NotFound }
]

to:

const routes = [
    { path: '/', title: '', component: <Home /> },
    { path: '*', title: '', component: <NotFound /> }
]