嗨，我正在尝试建立一个react的基本示例，这是我显示页面的代码。您能否建议我如何更好地构成这一要素。我要导入到我的应用程序中的Header.js有什么问题？
Header.js
import Jumbotron from "react-bootstrap/Jumbotron";
import ButtonGroup from "react-bootstrap/ButtonGroup";
import Button from "react-bootstrap/Button";
export default class Header extends React.Component {
render() {
return (
<Jumbotron fluid>
<h1 classname="header">Welcome to Zach's page</h1>
<ButtonGroup aria-label="Basic example">
<Button variant="secondary">Left</Button>
<Button variant="secondary">Middle</Button>
<Button variant="secondary">Right</Button>
</ButtonGroup>
</Jumbotron>
);
}
}
App.js
import React from "react";
// Importing the Bootstrap CSS
import "bootstrap/dist/css/bootstrap.min.css";
import "./App.css";
import Header from "../src/Header";
import HeaderNavigation from "../src/HeaderNavigation";
import Form from "../src/Form";
import Body from "../src/Body";
const App = () => (
<div>
<div classname="container">
<HeaderNavigation />
<div classname="contents">{this.props.activeRouteHandler()}</div>
</div>
<Header />
<Body>
<Form />
</Body>
</div>
);
export default App;
Apptest.js
import React from "react";
import ReactDOM from "react-dom";
import App from "./App";
import Header from "../src/Header";
import HeaderNavigation from "../src/HeaderNavigation";
import Form from "../src/Form";
import Body from "../src/Body";
it("renders without crashing",() => {
const div = document.createElement("div");
ReactDOM.render(<App />,<Header />,<HeaderNavigation /> <Form />,<Body />);
ReactDOM.unmountComponentAtNode(div);
});
错误
'React' is not defined. (no-undef)
eslint
/src/Jumpotron.js: Unterminated JSX contents (16:14) 14 | <Button variant="secondary">Middle</Button> 15 | <Button variant="secondary">Right</Button> > 16 | </ButtonGroup> | ^ 17 |
Parsing error: Adjacent JSX elements must be wrapped in an enclosing tag. Did you want a JSX fragment <>...</>? 9 | it("renders without crashing",() => { 10 | const div = document.createElement("div"); > 11 | ReactDOM.render(<App />,<Body />); | ^ 12 | ReactDOM.unmountComponentAtNode(div); 13 | }); 14 | (null)