Javascript 未捕获错误：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_Expo_Google Fonts

Javascript 未捕获错误：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

Javascript 未捕获错误：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,expo,google-fonts,Javascript,React Native,Expo,Google Fonts,我正在尝试在我的应用程序中使用google字体，当我尝试将其用作IBMPlexSans字体时，我遇到了这个错误。。。 '未捕获错误：元素类型无效：需要字符串（对于嵌入式组件）或类/函数（对于复合组件），但得到：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”。谁能帮我一把吗 import React, { Component } from 'react' import { AppLoading } from 'expo' import { useF

我正在尝试在我的应用程序中使用google字体，当我尝试将其用作IBMPlexSans字体时，我遇到了这个错误。。。 '未捕获错误：元素类型无效：需要字符串（对于嵌入式组件）或类/函数（对于复合组件），但得到：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”。谁能帮我一把吗

import React, { Component } from 'react'
import { AppLoading } from 'expo'
import {
  useFonts,
  IBMPlexSans_100Thin,
  IBMPlexSans_100Thin_Italic,
  IBMPlexSans_200ExtraLight,
  IBMPlexSans_200ExtraLight_Italic,
  IBMPlexSans_300Light,
  IBMPlexSans_300Light_Italic,
  IBMPlexSans_400Regular,
  IBMPlexSans_400Regular_Italic,
  IBMPlexSans_500Medium,
  IBMPlexSans_500Medium_Italic,
  IBMPlexSans_600SemiBold,
  IBMPlexSans_600SemiBold_Italic,
  IBMPlexSans_700Bold,
  IBMPlexSans_700Bold_Italic,
} from '@expo-google-fonts/ibm-plex-sans';

import { StyleSheet, Text, View, TouchableOpacity, ScrollView, Dimensions, ImageBackground } from 'react-native';




export default function RegisterScreen (props) {

    let [fontsLoaded] = useFonts({
        IBMPlexSans_100Thin,
        IBMPlexSans_100Thin_Italic,
        IBMPlexSans_200ExtraLight,
        IBMPlexSans_200ExtraLight_Italic,
        IBMPlexSans_300Light,
        IBMPlexSans_300Light_Italic,
        IBMPlexSans_400Regular,
        IBMPlexSans_400Regular_Italic,
        IBMPlexSans_500Medium,
        IBMPlexSans_500Medium_Italic,
        IBMPlexSans_600SemiBold,
        IBMPlexSans_600SemiBold_Italic,
        IBMPlexSans_700Bold,
        IBMPlexSans_700Bold_Italic,
      });
     
      if (!fontsLoaded) {
        return <AppLoading />;
      }

    return (

        <View>
           <Text style={{ fontFamily: 'IBMPlexSans_100Thin' }}>Text Example</Text>
        </View>
    )

}

import React，{Component}来自“React”
从“expo”导入{AppLoading}
进口{
使用字体，
IBMPlexSans_100Thin，
IBMPlexSans_100Thin_Italic，
IBMPlexSans_200ExtraLight，
IBMPlexSans_200ExtraLight_Italic，
IBMPlexSans_300灯，
IBMPlexSans_300浅斜体，
IBMPlexSansƐu常规，
IBMPlexSans\u 400常规\u斜体，
Imbplexsans_500中等，
IBMPlexSans_500中斜体，
IBMPlexSansɘ半黑体，
IBMPlexSans_600半黑体_斜体，
IBMPlexSans_700Bold，
IBMPlexSans_700Bold_斜体，
}来自“@expo google fonts/ibm plex sans”；
从“react native”导入{样式表、文本、视图、TouchableOpacity、ScrollView、维度、ImageBackground}；
导出默认功能注册表屏幕（道具）{
让[fontsLoaded]=使用字体({
IBMPlexSans_100Thin，
IBMPlexSans_100Thin_Italic，
IBMPlexSans_200ExtraLight，
IBMPlexSans_200ExtraLight_Italic，
IBMPlexSans_300灯，
IBMPlexSans_300浅斜体，
IBMPlexSansƐu常规，
IBMPlexSans\u 400常规\u斜体，
Imbplexsans_500中等，
IBMPlexSans_500中斜体，
IBMPlexSansɘ半黑体，
IBMPlexSans_600半黑体_斜体，
IBMPlexSans_700Bold，
IBMPlexSans_700Bold_斜体，
});
如果（！fontsLoaded）{
返回；
}
返回(
文本示例
)
}

首先，像这样安装

expo-app-load

npm install expo-app-loading

import * as Font from 'expo-font';
import {
  IBMPlexSans_100Thin,
  IBMPlexSans_100Thin_Italic,
  IBMPlexSans_200ExtraLight,
  IBMPlexSans_200ExtraLight_Italic,
  IBMPlexSans_300Light,
  IBMPlexSans_300Light_Italic,
  IBMPlexSans_400Regular,
  IBMPlexSans_400Regular_Italic,
  IBMPlexSans_500Medium,
  IBMPlexSans_500Medium_Italic,
  IBMPlexSans_600SemiBold,
  IBMPlexSans_600SemiBold_Italic,
  IBMPlexSans_700Bold,
  IBMPlexSans_700Bold_Italic,
} from '@expo-google-fonts/ibm-plex-sans';

const useFonts = async () => {
  await Font.loadAsync({
    IBMPlexSans_100Thin,
    IBMPlexSans_100Thin_Italic,
    IBMPlexSans_200ExtraLight,
    IBMPlexSans_200ExtraLight_Italic,
    IBMPlexSans_300Light,
    IBMPlexSans_300Light_Italic,
    IBMPlexSans_400Regular,
    IBMPlexSans_400Regular_Italic,
    IBMPlexSans_500Medium,
    IBMPlexSans_500Medium_Italic,
    IBMPlexSans_600SemiBold,
    IBMPlexSans_600SemiBold_Italic,
    IBMPlexSans_700Bold,
    IBMPlexSans_700Bold_Italic,
  });
};

export default useFonts;

import React, { Component, useState } from 'react';
import AppLoading from 'expo-app-loading';

import {
  StyleSheet,
  Text,
  View,
  TouchableOpacity,
  ScrollView,
  Dimensions,
  ImageBackground,
} from 'react-native';

import useFonts from './hooks/useFonts';

export default function RegisterScreen(props) {
  const [IsReady, SetIsReady] = useState(false);

  const LoadFontsAndRestoreToken = async () => {
    await useFonts();
  };

  if (!IsReady) {
    return (
      <AppLoading
        startAsync={LoadFontsAndRestoreToken}
        onFinish={() => SetIsReady(true)}
        onError={() => {}}
      />
    );
  }

  return (
    <View>
      <Text style={{ fontFamily: 'IBMPlexSans_100Thin' }}>Text Example</Text>
      <Text>Normal Text</Text>
    </View>
  );
}

然后安装expo字体


npm install expo-font

在App.js
所在的位置创建一个名为hooks
的文件夹
在hooks
文件夹中创建一个名为useFonts.js的文件
那么您的useFonts.js
应该如下所示
npm install expo-app-loading

import * as Font from 'expo-font';
import {
  IBMPlexSans_100Thin,
  IBMPlexSans_100Thin_Italic,
  IBMPlexSans_200ExtraLight,
  IBMPlexSans_200ExtraLight_Italic,
  IBMPlexSans_300Light,
  IBMPlexSans_300Light_Italic,
  IBMPlexSans_400Regular,
  IBMPlexSans_400Regular_Italic,
  IBMPlexSans_500Medium,
  IBMPlexSans_500Medium_Italic,
  IBMPlexSans_600SemiBold,
  IBMPlexSans_600SemiBold_Italic,
  IBMPlexSans_700Bold,
  IBMPlexSans_700Bold_Italic,
} from '@expo-google-fonts/ibm-plex-sans';

const useFonts = async () => {
  await Font.loadAsync({
    IBMPlexSans_100Thin,
    IBMPlexSans_100Thin_Italic,
    IBMPlexSans_200ExtraLight,
    IBMPlexSans_200ExtraLight_Italic,
    IBMPlexSans_300Light,
    IBMPlexSans_300Light_Italic,
    IBMPlexSans_400Regular,
    IBMPlexSans_400Regular_Italic,
    IBMPlexSans_500Medium,
    IBMPlexSans_500Medium_Italic,
    IBMPlexSans_600SemiBold,
    IBMPlexSans_600SemiBold_Italic,
    IBMPlexSans_700Bold,
    IBMPlexSans_700Bold_Italic,
  });
};

export default useFonts;

import React, { Component, useState } from 'react';
import AppLoading from 'expo-app-loading';

import {
  StyleSheet,
  Text,
  View,
  TouchableOpacity,
  ScrollView,
  Dimensions,
  ImageBackground,
} from 'react-native';

import useFonts from './hooks/useFonts';

export default function RegisterScreen(props) {
  const [IsReady, SetIsReady] = useState(false);

  const LoadFontsAndRestoreToken = async () => {
    await useFonts();
  };

  if (!IsReady) {
    return (
      <AppLoading
        startAsync={LoadFontsAndRestoreToken}
        onFinish={() => SetIsReady(true)}
        onError={() => {}}
      />
    );
  }

  return (
    <View>
      <Text style={{ fontFamily: 'IBMPlexSans_100Thin' }}>Text Example</Text>
      <Text>Normal Text</Text>
    </View>
  );
}

你的App.js
应该是这样的
npm install expo-app-loading

import * as Font from 'expo-font';
import {
  IBMPlexSans_100Thin,
  IBMPlexSans_100Thin_Italic,
  IBMPlexSans_200ExtraLight,
  IBMPlexSans_200ExtraLight_Italic,
  IBMPlexSans_300Light,
  IBMPlexSans_300Light_Italic,
  IBMPlexSans_400Regular,
  IBMPlexSans_400Regular_Italic,
  IBMPlexSans_500Medium,
  IBMPlexSans_500Medium_Italic,
  IBMPlexSans_600SemiBold,
  IBMPlexSans_600SemiBold_Italic,
  IBMPlexSans_700Bold,
  IBMPlexSans_700Bold_Italic,
} from '@expo-google-fonts/ibm-plex-sans';

const useFonts = async () => {
  await Font.loadAsync({
    IBMPlexSans_100Thin,
    IBMPlexSans_100Thin_Italic,
    IBMPlexSans_200ExtraLight,
    IBMPlexSans_200ExtraLight_Italic,
    IBMPlexSans_300Light,
    IBMPlexSans_300Light_Italic,
    IBMPlexSans_400Regular,
    IBMPlexSans_400Regular_Italic,
    IBMPlexSans_500Medium,
    IBMPlexSans_500Medium_Italic,
    IBMPlexSans_600SemiBold,
    IBMPlexSans_600SemiBold_Italic,
    IBMPlexSans_700Bold,
    IBMPlexSans_700Bold_Italic,
  });
};

export default useFonts;

import React, { Component, useState } from 'react';
import AppLoading from 'expo-app-loading';

import {
  StyleSheet,
  Text,
  View,
  TouchableOpacity,
  ScrollView,
  Dimensions,
  ImageBackground,
} from 'react-native';

import useFonts from './hooks/useFonts';

export default function RegisterScreen(props) {
  const [IsReady, SetIsReady] = useState(false);

  const LoadFontsAndRestoreToken = async () => {
    await useFonts();
  };

  if (!IsReady) {
    return (
      <AppLoading
        startAsync={LoadFontsAndRestoreToken}
        onFinish={() => SetIsReady(true)}
        onError={() => {}}
      />
    );
  }

  return (
    <View>
      <Text style={{ fontFamily: 'IBMPlexSans_100Thin' }}>Text Example</Text>
      <Text>Normal Text</Text>
    </View>
  );
}

import React，{Component，useState}来自'React'；
从“expo应用程序加载”导入应用程序加载；
进口{
样式表，
文本，
看法
可触摸不透明度，
滚动视图，
尺寸，
图像背景，
}从“反应本机”；
从“/hooks/useFonts”导入useFonts；
导出默认功能注册表屏幕（道具）{
const[IsReady，SetIsReady]=useState（false）；
const LoadFontsAndRestoreToken=async（）=>{
等待使用字体（）；
};
如果（！IsReady）{
返回(
SetIsReady（真）}
onError={（）=>{}
/>
);
}
返回(
文本示例
普通文本
);
}