我丢失了一个React片段:

function Bar({ children }) {

  return (
    <div>
     {children}
    </div>
  );
}

function Foo() {
  return (
    <Bar>
      <Baz/>
      <Qux/>
    </Bar>
  );
}

上面的代码抛出上面的错误。但这就解决了问题:

<Bar>
  <>
    <Baz/>
    <Qux/>
  </>
</Bar>

这是一个在某种程度上必须调试的错误。正如已经说过很多次，不恰当的导入/导出会导致这个错误，但令人惊讶的是，我从我的react-router-dom认证设置中的一个小错误中得到了这个错误，下面是我的情况:

错误的设置:

const PrivateRoute = ({ component: Component, ...rest }) => (
    <Route
        {...rest}
        render={(props) => (token ? <Component {...props} /> : <Redirect to={{ pathname: "/login" }} />)}
    />
);

正确设置:

const PrivateRoute = ({ component: Component, token, ...rest }) => (
    <Route
        {...rest}
        render={(props) => (token ? <Component {...props} /> : <Redirect to={{ pathname: "/login" }} />)}
    />
);

唯一的区别是我在PrivateRoute组件中解构了令牌。顺便说一下，令牌是从localstorage获取的，像这样const token = localstorage . getitem ("authUser");所以如果它不在那里，我知道用户没有验证。这也会导致错误。

// @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>

对于我来说，这发生在我试图将命名导入作为默认导入时，所以我得到了这个错误

import ProductCard from '../../../components/ProductCard' // that what caused the issue

Error: Element 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, or you might have mixed up default and named imports.

Check the render method of `TopVente`.

所以我必须通过名称导入来修复它

import { ProductCard } from '../../../components/ProductCard'

我也得到了这个错误。

我用的是:

import BrowserRouter from 'react-router-dom';

费克斯是这样做的:

import {BrowserRouter} from 'react-router-dom';

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>
  );
}