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javascript - 模块解析失败：使用 webpack 5 时出现意外的令牌

问题描述

当我使用 webpack 5 编译我的 react 项目时，显示此错误：

[root@VM-0-16-centos cruise-web]# yarn build
yarn run v1.22.10
$ webpack --config config/dev.config.js
[webpack-cli] Compilation finished
assets by status 341 bytes [cached] 1 asset
./src/index.js 630 bytes [built] [code generated] [1 error]

ERROR in ./src/index.js 10:2
Module parse failed: Unexpected token (10:2)
You may need an appropriate loader to handle this file type, currently no loaders are configured to process this file. See https://webpack.js.org/concepts#loaders
| 
| ReactDOM.render(
>   <React.StrictMode>
|     <Provider store={store}>
|       {routes}

webpack 5.6.0 compiled with 1 error in 126 ms
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

这是我的index.js：

import React from 'react';
import ReactDOM from 'react-dom';
import './index.css';
import { Provider } from 'react-redux';
import reportWebVitals from './reportWebVitals';
import routes from './routes/routes';
import store from './store';

ReactDOM.render(
  <React.StrictMode>
    <Provider store={store}>
      {routes}
    </Provider>
  </React.StrictMode>,
  document.getElementById('root')
);

// If you want to start measuring performance in your app, pass a function
// to log results (for example: reportWebVitals(console.log))
reportWebVitals();

这是我的package.json配置：

"scripts": {
    "start": "react-scripts start",
    "build": "webpack --config config/dev.config.js",
    "test": "react-scripts test",
    "eject": "react-scripts eject"
  }

这是dev.config.js配置：

const path = require('path');

module.exports = {
  module: {
    rules: [
    {
        test: /\.css$/i,
        use: [
        "style-loader",
        "css-loader",
        {
            loader: "postcss-loader",
            options: {
            postcssOptions: {
                plugins: [
                [
                    "postcss-preset-env",
                    {
                    // Options
                    },
                ],
                ],
            },
            },
        },
        ],
    },
    ],
  },
  entry: './src/index.js',
  output: {
    filename: 'main.js',
    path: path.resolve(__dirname, 'build'),
  },
};

我应该怎么做才能解决这个问题？

标签： javascriptwebpack-5

解决方案

您需要为所有.js文件定义一个规则并添加babel-loader到其中：https ://github.com/babel/babel-loader

Webpack 的工作方式是你必须告诉它为每个特定的文件类型扩展名做什么（或者你定义你的规则）。Javascript，本质上是不理解的JSX，您需要使用加载器，以便可以将其解析为常规且可用的 Javascript。Webpack 默认不理解 JSX。

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