反应。类型无效——期望为字符串

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

这意味着您的导入/导出不正确。

检查新增的导入/导出。在我的例子中，我不必要地使用了大括号。当我去掉这些花括号时，问题就自动解决了。

import { OverlayTrigger } from 'react-bootstrap/OverlayTrigger';

2020-11-12 10:47:15

其他回答

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。

2019-07-12 08:03:37

// @flow

import React from 'react';
import { styleLocal } from './styles';
import {
  View,
  Text,
  TextInput,
  Image,
} from 'react-native';
import { TouchableOpacity } from 'react-native-gesture-handler';

export default React.forwardRef((props, ref) => {
const { onSeachClick, onChangeTextSearch , ...otherProps } = props;

  return (
        <View style={styleLocal.sectionStyle}>
        <TouchableOpacity onPress={onSeachClick}>
            <Image                              
                    source={require('../../assets/imgs/search.png')}
                    style={styleLocal.imageStyle} />
                </TouchableOpacity>
            <TextInput
                style={{ flex: 1, fontSize: 18 }}
                placeholder="Search Here"
                underlineColorAndroid="transparent"
                onChangeText={(text) => { onChangeTextSearch(text) }}
            />
        </View>
  );
});
 import IGPSSearch from '../../components/IGPSSearch';
<Search onSeachClick={onSeachClick} onChangeTextSearch= {onChangeTextSearch}> </Search>

2021-02-03 20:05:14

如果在测试组件时出现此错误，请确保每个子组件在单独运行时都能正确呈现，如果其中一个子组件依赖于外部资源来呈现，请尝试使用jest或任何其他mock库来模拟它:

示例:

jest.mock('pathToChildComponent', () => 'mock-child-component')

2019-06-11 14:13:23

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'

import { Provider } from 'react-redux'

2018-03-13 15:21:42

在我的例子中，我添加了相同的自定义组件作为道具，而不是实际的道具

   import AddAddress from '../../components/Manager/AddAddress';
    
    class Add extends React.PureComponent {
      render() {
        const {
          history,
          addressFormData,
          formErrors,
          addressChange,
          addAddress,
          isDefault,
          defaultChange
        } = this.props;

错误:

    return (
        <AddAddress
          addressFormData={addressFormData}
          formErrors={formErrors}
          addressChange={addressChange}
          addAddress={AddAddress} // here i have used the Component name as probs in same component itself instead of prob
          isDefault={isDefault}
          defaultChange={defaultChange}
        />
      </SubPage>

解决方案:

return (
    <AddAddress
      addressFormData={addressFormData}
      formErrors={formErrors}
      addressChange={addressChange}
      addAddress={addAddress} // removed the component name and give prob name
      isDefault={isDefault}
      defaultChange={defaultChange}
    />
  </SubPage>

2021-02-21 14:36:53

反应。类型无效——期望为字符串

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