我得到这个错误:
Uncaught Error: Invariant Violation: Element type is invalid: expected a string (for built-in components) or a class/function (for composite components) but got: object.
这是我的代码:
var React = require('react')
var ReactDOM = require('react-dom')
var Router = require('react-router')
var Route = Router.Route
var Link = Router.Link
var App = React.createClass({
render() {
return (
<div>
<h1>App</h1>
<ul>
<li><Link to="/about">About</Link></li>
</ul>
</div>
)
}
})
var About = require('./components/Home')
ReactDOM.render((
<Router>
<Route path="/" component={App}>
<Route path="about" component={About} />
</Route>
</Router>
), document.body)
我的家。jsx文件:
var React = require('react');
var RaisedButton = require('material-ui/lib/raised-button');
var Home = React.createClass({
render:function() {
return (
<RaisedButton label="Default" />
);
},
});
module.exports = Home;
我错误地试图从react-native而不是native-base导入容器和内容。
错误，因为这一行:
import { ActivityIndicator, RefreshControl, StyleSheet, View, Keyboard, Container, Content } from 'react-native';
下面是代码修复:
import { ActivityIndicator, RefreshControl, StyleSheet, View, Keyboard } from 'react-native';
import { Container, Content} from 'native-base';
我也遇到了同样的问题，并意识到我在JSX标记中提供了一个未定义的React组件。问题是要渲染的react组件是动态计算的，它最终没有定义!
错误说明:
不变性违反:元素类型无效:期望为字符串(对于内置组件)或类/函数(对于复合组件)，但得到:undefined。您可能忘记从定义组件的文件中导出组件。检查C.的渲染方法，
产生此错误的示例:
var componentA = require('./components/A');
var componentB = require('./components/B');
const templates = {
a_type: componentA,
b_type: componentB
}
class C extends React.Component {
constructor(props) {
super(props);
}
// ...
render() {
//Let´s say that depending on the uiType coming in a data field you end up rendering a component A or B (as part of C)
const ComponentTemplate = templates[this.props.data.uiType];
return <ComponentTemplate></ComponentTemplate>
}
// ...
}
问题是提供了一个无效的“uiType”，因此产生了未定义的结果:
模板['无效字符串']
@Balasubramani M救了我。想再加一个来帮助人们。当你把太多的东西粘在一起，对版本漫不经心时，这就是问题所在。我更新了material-ui的一个版本，需要更改
import Card, {CardContent, CardMedia, CardActions } from "@material-ui/core/Card";
:
import Card from '@material-ui/core/Card';
import CardActions from '@material-ui/core/CardActions';
import CardContent from '@material-ui/core/CardContent';
import CardMedia from '@material-ui/core/CardMedia';
