Javascript 元素类型无效。。?
我是一个新的反应者,我得到了以下警告: 元素类型无效:应为字符串(对于内置组件)或类/函数(对于复合组件),但得到:对象。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Javascript 元素类型无效。。?,javascript,reactjs,Javascript,Reactjs,我是一个新的反应者,我得到了以下警告: 元素类型无效:应为字符串(对于内置组件)或类/函数(对于复合组件),但得到:对象。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 import App from "./App"; 6 | //import * as serviceWorker from "./serviceWorker"; 7 | > 8 | ReactDOM.render( 9 | <
import App from "./App";
6 | //import * as serviceWorker from "./serviceWorker";
7 |
> 8 | ReactDOM.render(
9 | <BrowserRouter>
10 | <App />
11 | </BrowserRouter>,
My classes are: (index.js)
import React from "react";
import ReactDOM from "react-dom";
import { BrowserRouter } from "react-router-dom";
import App from "./App";
//import * as serviceWorker from "./serviceWorker";
ReactDOM.render(
<BrowserRouter>
<App />
</BrowserRouter>,
document.getElementById("root")
);
//serviceWorker.unregister();
从“/App”导入应用程序;
6 |//作为serviceWorker从“/serviceWorker”导入*;
7 |
>8 | ReactDOM.render(
9 |
10 |
患者
添加患者
);
}
}
导出默认应用程序;
我一直试图理解这个错误,但到目前为止没有任何线索,即使在尝试了互联网上的多个建议之后。编辑:进一步检查后,您似乎只是错误地导出了应用程序组件 更改:
类应用程序扩展了App.js中的组件{
对此:类应用程序扩展了React.Component{
这应该可以解决您的问题。因为存在导入反应,{Component}…这样可以。其他导入的文件可能有问题。
import React, { Component } from "react";
import { Switch, Route, Link } from "react-router-dom";
import "bootstrap/dist/css/bootstrap.min.css";
import "./App.css";
import AddPatient from "./components/add-patient.component";
import Patient from "./components/patient.component";
import PatientsList from "./components/patient-list.component";
class App extends Component {
render() {
return (
<div>
<nav className="navbar navbar-expand navbar-dark bg-dark">
<a href="/doctor/patients" className="navbar-brand">
ReactApp
</a>
<div className="navbar-nav mr-auto">
<li className="nav-item">
<Link to={"/doctor/patients"} className="nav-link">
Patients
</Link>
</li>
<li className="nav-item">
<Link to={"/doctor/newpatient"} className="nav-link">
Add Patient
</Link>
</li>
</div>
</nav>
<div className="container mt-3">
<Switch>
<Route exact path={["/", "/doctor/patients"]} component={PatientsList} />
<Route exact path="/doctor/newpatient" component={AddPatient} />
<Route path="/doctor/patient/:id" component={Patient} />
</Switch>
</div>
</div>
);
}
}
export default App;