警告：React.createElement：类型无效

Question

我正在尝试构建一个反应本机博览会应用程序并收到此错误api.jsexport const fetchMeetups = () =>    fetch('http://localhost:3000/api/meetups')        .then(res => res.json());应用程序.jsimport * as React from 'react';import { Platform, StyleSheet, Text, View, ActivityIndicator } from 'react-native';import { fetchMeetups } from './constants/api'; const instructions = Platform.select({  ios: `Press Cmd+R to reload,\nCmd+D or shake for dev menu`,  android: `Double tap R on your keyboard to reload,\nShake or press menu button for dev menu`,});class App extends React.Component{  static defaultProps = {    fetchMeetups  }  state = {    loading: false,    meetups: []  }  async componentDidMount(){    this.setState({loading: true});    const data = await this.props.fetchMeetups();    setTimeout(() => this.setState({loading: false, meetups: data.meetups}),2000)  }  render(){    if(this.state.loading){      return(        <ActivityIndicator size="large"/>      )    }    return (      <View style={styles.container}>        <Text>MeetupME</Text>      </View>    );  }}const styles = StyleSheet.create({  container: {    flex: 1,    justifyContent: 'center',    alignItems: 'center',    backgroundColor: '#F5FCFF',  },  welcome: {    fontSize: 20,    textAlign: 'center',    margin: 10,  },  instructions: {    textAlign: 'center',    color: '#333333',    marginBottom: 5,  },});索引.jsimport { registerRootComponent } from 'expo';import App from './App';// registerRootComponent calls AppRegistry.registerComponent('main', () => App);// It also ensures that whether you load the app in the Expo client or in a native build,// the environment is set up appropriatelyregisterRootComponent(App);

Answer 1

看起来像 App.js 缺少默认导出。

index.js 尝试导入默认导出 （），因此您只需将以下内容添加到 App.js。例如，到文件末尾。import App from './App'

export default App