javascript - Webpack 模式和加载器问题

Question

我正在学习建立自己的 webpack，但遇到了一些奇怪的问题。

这是我的 webpack.development.config.js：

const path = require('path');
const CleanWebpackPlugin = require('clean-webpack-plugin');
const HtmlWebpackPlugin = require('html-webpack-plugin');

module.export = {
  entry: './src/index.js',
  output: {
    filename: '[name].bundle.js',
    path: path.resolve(__dirname, './dist'),
    publicPath: ''
  },
  mode: 'development',
  devServer: {
    contentBase: path.resolve(__dirname, './dist'),
    index: 'index.html',
    port: 3000
  },
  modules: {
    rules: [
      {
        test: /\.(png|jpg)$/,
        use: ['file-loader']
      },
      {
        test: /\.(css)$/,
        use: ['style-loader', 'css-loader']
      },
      {
        test: /\.(js|jsx)$/,
        exclude: '/node_modules/',
        use: {
          loader: 'babel-loader',
          options: {
            presets: ['@babel/env', '@babel/preset-react'],
            plugins: ['transform-class-properties']
          }
        }
      }
    ]
  },
  plugins: [
    new CleanWebpackPlugin(),
    new HtmlWebpackPlugin({
      filename: 'index.html',
      description: 'Sample code',
    })
  ]
}

当我运行以下命令时：

webpack-dev-server --config ./webpack.development.config.js --hot

这是我控制台中的输出：

I:\sample>npm run dev

> sample@0.0.0 dev I:\datum_gui
> webpack-dev-server --config ./webpack.development.config.js --hot

i ｢wds｣: Project is running at http://localhost:8080/

WARNING in configuration
The 'mode' option has not been set, [...]

ERROR in ./src/index.js 23:4
Module parse failed: Unexpected token (23:4)
You may need an appropriate loader to handle this file type.
| const render = (Component) => {
|   ReactDOM.render(
>     <AppContainer>
|       <CookiesProvider>
|         <Provider store={store}>
 @ multi (webpack)-dev-server/client?http://localhost:8080 (webpack)/hot/dev-server.js ./src main[2]
i ｢wdm｣: Failed to compile.

我有几个问题：

1) 为什么代码似乎无法识别我指定的端口 3000，而是默认为端口 8080？

2）我已经设置了模式：'development'，但是有一个警告，因为我已经默认为'production'

3）我错过了什么加载器，代码无法理解我的 index.js？

节点包：

• "babel-loader": "^8.0.5",
• "webpack": "^4.33.0",
• "webpack-cli": "^3.2.3",
• "webpack-dev-server": "^3.1.14",
• "babel-plugin-transform-class-properties": "^6.24.1",
• "@babel/preset-env": "1.4.0",
• "@babel/preset-react": "7.0.0",

标签： javascriptreactjswebpack-dev-serverwebpack-4

Answer 1

您收到错误的原因是因为您忘记添加jsx到加载程序

{            // \/ forgot to add jsx here
  test: /\.(js|jsx)$/,
  exclude: '/node_modules/',
  use: {
    loader: 'babel-loader',
    options: {                   // also need @babel/preset-react
      presets: ['@babel/env', '@babel/preset-react'],
      plugins: ['transform-class-properties']
    }
  }
}

编辑：

你还需要@babel/preset-react

只需运行npm i @babel/preset-react并将其添加到options.presets