Javascript npm,错误:元素类型无效:需要字符串(对于内置组件)或类/函数(对于复合组件),但得到:未定义
React native、npm、expo。 IOS模拟机 我得到这个错误,我不知道为什么 警告:React.createElement:类型无效--应为字符串(对于内置组件)或类/函数(对于复合组件),但Get:未定义。您可能忘记了从定义组件的文件中导出组件,或者您可能混淆了默认导入和命名导入 请在App.js:23查看您的代码Javascript npm,错误:元素类型无效:需要字符串(对于内置组件)或类/函数(对于复合组件),但得到:未定义,javascript,react-native,npm,expo,react-native-ios,Javascript,React Native,Npm,Expo,React Native Ios,React native、npm、expo。 IOS模拟机 我得到这个错误,我不知道为什么 警告:React.createElement:类型无效--应为字符串(对于内置组件)或类/函数(对于复合组件),但Get:未定义。您可能忘记了从定义组件的文件中导出组件,或者您可能混淆了默认导入和命名导入 请在App.js:23查看您的代码 in App (created by ExpoRoot) in ExpoRoot (at renderApplication.js:45) in RCTView (a
in App (created by ExpoRoot)
in ExpoRoot (at renderApplication.js:45)
in RCTView (at View.js:34)
in View (at AppContainer.js:106)
in DevAppContainer (at AppContainer.js:121)
in RCTView (at View.js:34)
in View (at AppContainer.js:132)
in AppContainer (at renderApplication.js:39)
在captureConsoleStackTrace中的节点_modules/expo/build/logs/LogSerialization.js:155:14处
在serializeLogDataAsync中的节点_modules/expo/build/logs/LogSerialization.js:41:26处
- 。。。9个来自框架内部的堆栈框架
import * as Font from 'expo-font';
import { AppLoading } from 'expo';
import { enableScreens } from 'react-native-screens';
import MealsNavigator from './navigation/MealsNavigator';
enableScreens();
const fetchFonts = () => {
return Font.loadAsync({
'open-sans': require('./assets/fonts/OpenSans-Regular.ttf'),
'open-sans-bold': require('./assets/fonts/OpenSans-Bold.ttf')
});
};
function App() {
const [fontLoaded, setFontLoaded] = useState(false);
if (!fontLoaded) {
return (
<AppLoading
startAsync={fetchFonts}
onFinish={() => setFontLoaded(true)}
onError={console.warn}
/>
);
}
return <MealsNavigator />;
}
export default App;
import*作为“expo字体”中的字体;
从“expo”导入{AppLoading};
从“react native screens”导入{enableScreens};
从“./navigation/MealsNavigator”导入MealsNavigator;
启用屏幕();
常量fetchFonts=()=>{
返回Font.loadAsync({
“开放SAN”:需要(“./assets/font/OpenSans Regular.ttf”),
“open sans bold”:需要(“./assets/font/OpenSans bold.ttf”)
});
};
函数App(){
常量[fontLoaded,setFontLoaded]=useState(false);
如果(!fontLoaded){
返回(
setFontLoaded(真)}
onError={console.warn}
/>
);
}
返回;
}
导出默认应用程序;
MealsNavigator:
import React from 'react';
import { Platform, Text } from 'react-native';
import {
createStackNavigator,
createBottomTabNavigator,
createAppContainer,
createDrawerNavigator
} from 'react-navigation';
import { Ionicons } from '@expo/vector-icons';
import { createMaterialBottomTabNavigator } from 'react-navigation-material-bottom-tabs';
import CategoriesScreen from '../screens/CategoriesScreen';
import CategoryMealsScreen from '../screens/CategoryMealsScreen';
import MealDetailScreen from '../screens/MealDetailScreen';
import FavoritesScreen from '../screens/FavoritesScreen';
import FiltersScreen from '../screens/FiltersScreen';
import Colors from '../constants/Colors';
const defaultStackNavOptions = {
headerStyle: {
backgroundColor: Platform.OS === 'android' ? Colors.primaryColor : ''
},
headerTitleStyle: {
fontFamily: 'open-sans-bold'
},
headerBackTitleStyle: {
fontFamily: 'open-sans'
},
headerTintColor: Platform.OS === 'android' ? 'white' : Colors.primaryColor,
headerTitle: 'A Screen'
};
const MealsNavigator = createStackNavigator(
{
Categories: {
screen: CategoriesScreen
},
CategoryMeals: {
screen: CategoryMealsScreen
},
MealDetail: MealDetailScreen
},
{
// initialRouteName: 'Categories',
defaultNavigationOptions: defaultStackNavOptions
}
);
const FavNavigator = createStackNavigator(
{
Favorites: FavoritesScreen,
MealDetail: MealDetailScreen
},
{
// initialRouteName: 'Categories',
defaultNavigationOptions: defaultStackNavOptions
}
);
const tabScreenConfig = {
Meals: {
screen: MealsNavigator,
navigationOptions: {
tabBarIcon: tabInfo => {
return (
<Ionicons name="ios-restaurant" size={25} color={tabInfo.tintColor} />
);
},
tabBarColor: Colors.primaryColor,
tabBarLabel:
Platform.OS === 'android' ? (
<Text style={{ fontFamily: 'open-sans-bold' }}>Meals</Text>
) : (
'Meals'
)
}
},
Favorites: {
screen: FavNavigator,
navigationOptions: {
tabBarIcon: tabInfo => {
return <Ionicons name="ios-star" size={25} color={tabInfo.tintColor} />;
},
tabBarColor: Colors.accentColor,
tabBarLabel:
Platform.OS === 'android' ? (
<Text style={{ fontFamily: 'open-sans-bold' }}>Favorites</Text>
) : (
'Favorites'
)
}
}
};
const MealsFavTabNavigator =
Platform.OS === 'android'
? createMaterialBottomTabNavigator(tabScreenConfig, {
activeTintColor: 'white',
shifting: true,
barStyle: {
backgroundColor: Colors.primaryColor
}
})
: createBottomTabNavigator(tabScreenConfig, {
tabBarOptions: {
labelStyle: {
fontFamily: 'open-sans'
},
activeTintColor: Colors.accentColor
}
});
const FiltersNavigator = createStackNavigator(
{
Filters: FiltersScreen
},
{
// navigationOptions: {
// drawerLabel: 'Filters!!!!'
// },
defaultNavigationOptions: defaultStackNavOptions
}
);
const MainNavigator = createDrawerNavigator(
{
MealsFavs: {
screen: MealsFavTabNavigator,
navigationOptions: {
drawerLabel: 'Meals'
}
},
Filters: FiltersNavigator
},
{
contentOptions: {
activeTintColor: Colors.accentColor,
labelStyle: {
fontFamily: 'open-sans-bold'
}
}
}
);
export default createAppContainer(MainNavigator);
从“React”导入React;
从“react native”导入{Platform,Text};
进口{
createStackNavigator,
CreateBoottomTabNavigator,
createAppContainer,
createDrawerNavigator
}从“反应导航”;
从“@expo/vector icons”导入{Ionicons};
从“反应导航材料底部选项卡”导入{createMaterialBottomTabNavigator};
从“../screens/CategoriesScreen”导入分类屏幕;
从“../screens/CategoryMalsScreen”导入CategoryMalsScreen;
从“../screens/MealDetailScreen”导入MealDetailScreen;
从“../screens/FavoriteScreen”导入FavoriteScreen;
从“../screens/FilterScreen”导入FilterScreen;
从“../constants/Colors”导入颜色;
const defaultStackNavOptions={
头型:{
backgroundColor:Platform.OS=='android'?Colors.primaryColor:'
},
头饰样式:{
fontFamily:“开放式无边框”
},
headerBackTitleStyle:{
fontFamily:“开放式SAN”
},
headerTintColor:Platform.OS=='android'?'white':Colors.primaryColor,
标题:“屏幕”
};
const MealsNavigator=createStackNavigator(
{
类别:{
屏幕:分类屏幕
},
类别:{
屏幕:CategoryMalsScreen
},
Mealdeail:Mealdeail屏幕
},
{
//initialRouteName:“类别”,
defaultNavigationOptions:defaultStackNavOptions
}
);
const FavNavigator=createStackNavigator(
{
收藏夹:收藏夹屏幕,
Mealdeail:Mealdeail屏幕
},
{
//initialRouteName:“类别”,
defaultNavigationOptions:defaultStackNavOptions
}
);
常量选项卡屏幕配置={
膳食:{
屏幕:MealsNavigator,
导航选项:{
tabBarIcon:tabInfo=>{
返回(
);
},
tabBarColor:Colors.primaryColor,
tabBarLabel:
Platform.OS==='android'(
餐
) : (
“膳食”
)
}
},
收藏夹:{
屏幕:FavNavigator,
导航选项:{
tabBarIcon:tabInfo=>{
返回;
},
tabBarColor:Colors.accentColor,
tabBarLabel:
Platform.OS==='android'(
最爱
) : (
“收藏夹”
)
}
}
};
const MealsFavTabNavigator=
Platform.OS==='android'
? createMaterialBottomTabNavigator(tabScreenConfig{
activeTintColor:'白色',
是的,
酒吧风格:{
背景颜色:Colors.primaryColor
}
})
:CreateBoottomTabNavigator(tabScreenConfig{
选项卡选项:{
标签样式:{
fontFamily:“开放式SAN”
},
activeTintColor:Colors.accentColor
}
});
const FiltersNavigator=createStackNavigator(
{
过滤器:过滤器屏幕
},
{
//导航选项:{
//抽屉标签:“过滤器!!!!”
// },
defaultNavigationOptions:defaultStackNavOptions
}
);
const main navigator=createDrawerNavigator(
{
米尔斯法夫斯:{
屏幕:MealsFavTabNavigator,
导航选项:{
抽屉标签:“膳食”
}
},
过滤器:过滤器导航器
},
{
内容选项:{
activeTintColor:Colors.accentColor,
标签样式:{
fontFamily:“开放式无边框”
}
}
}
);
导出默认createAppContainer(MainNavigator);
我不熟悉React-Native,但通过查看文档,似乎expo
没有导出任何名为AppLoading
的组件。现在看来,您需要替换“expo”中的import{AppLoading}代码>使用从“expo应用程序加载”导入应用程序加载代码>(您可能需要npm安装expo应用程序加载
首先)非常感谢,我使用了您建议的导入并尝试了“npm安装expo应用程序加载”,但没有成功,然后我尝试了“expo安装expo应用程序加载”,成功了!对不起,我没有注意到安装命令不同。为误导而道歉,为注意到这一点而做得好!