我试图了解 React、Babel 和 Webpack 如何相互交互，但我收到以下错误:Uncaught TypeError: Super expression must either be null or a function。 CSS 呈现得很好，但 HTML 不是，尽管我能够在控制台中看到它(查看下图)。 有什么建议么？
package.json
{
"name": "react-raw",
"version": "1.0.0",
"description": "",
"main": "index.js",
"babel": {
"presets": [
"@babel/preset-env",
"@babel/preset-react"
]
},
"scripts": {
"start": "webpack-dev-server --open"
},
"keywords": [],
"author": "",
"license": "ISC",
"dependencies": {
"react": "^16.8.4",
"react-dom": "^16.8.4"
},
"devDependencies": {
"@babel/core": "^7.4.0",
"@babel/preset-env": "^7.4.1",
"@babel/preset-react": "^7.0.0",
"babel-loader": "^8.0.5",
"css-loader": "^2.1.1",
"html-webpack-plugin": "^3.2.0",
"style-loader": "^0.23.1",
"webpack": "^4.29.6",
"webpack-cli": "^3.3.0",
"webpack-dev-server": "^3.2.1"
}
}
索引.js
var React = require("react");
var ReactDOM = require("react-dom");
require("./index.css");
class App extends React.Component() {
render() {
return <div>Hello Christian!!</div>;
}
}
ReactDOM.render(<App />, document.getElementById("app"));
webpack.config.js
const path = require("path");
const HtmlWebpackPlugin = require("html-webpack-plugin"); //installed via npm
//const webpack = require("webpack"); //to access built-in plugins
module.exports = {
entry: "./app/index.js",
output: {
path: path.resolve(__dirname, "dist"),
filename: "index_bundle.js"
},
module: {
rules: [
{ test: /\.(js)$/, use: "babel-loader" },
{ test: /\.css$/, use: ["style-loader", "css-loader"] }
]
},
mode: "development",
plugins: [new HtmlWebpackPlugin({ template: "app/index.html" })]
};
index.html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<meta http-equiv="X-UA-Compatible" content="ie=edge" />
<title>React Raw</title>
</head>
<body>
<div id="app"></div>
</body>
</html>
最佳答案
您的问题出在您的 class 组件的签名上:
class App extends React.Component() {
render() {
return <div>Hello Christian!!</div>;
}
}
这是你需要声明它的方式:
class App extends React.Component{
render() {
return <div>Hello Christian!!</div>;
}
}
注意多余的 () 我省略了
您可以在 here 中阅读更多关于类的信息
关于javascript - React Component 不加载 Webpack 和 Babel 初学者级别，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/55296699/