如何让Webpack解析index.js文件中的JSX语法？

错误信息 #

ERROR in ./src/index.js 16:4
Module parse failed: Unexpected token (16:4)
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(
>     <h1>Hello World</h1>,
|   document.getElementById('root')
| );

导入语句 #

import React from 'react';
import ReactDOM from 'react-dom/client';

package.json相关配置 #

"scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "@babel/cli": "^7.21.0",
    "@babel/core": "^7.21.4",
    "@babel/preset-env": "^7.21.4",
    "@babel/preset-react": "^7.18.6",
    "babel-loader": "^9.1.2",
    "css-loader": "^6.7.3",
    "style-loader": "^3.3.2",
    "webpack": "^5.78.0",
    "webpack-cli": "^5.0.1"
  },
  "dependencies": {
    "core-js": "^3.30.0",
    "react": "^18.2.0",
    "react-dom": "^18.2.0"
  }
}

webpack.config.js配置 #

const path = require('path');

module.exports = {
  mode: 'production',
  entry: './src/index.js',
  output: {
    filename: 'main.js',
    path: path.resolve(__dirname, 'dist'),
  },
  module: {
    rules: [
      {
        test: /\.(?:js|mjs|cjs)$/,
        "exclude": [
          /node_modules[\\/]core-js/,
          /node_modules[\\/]webpack[\\/]buildin/,
        ],
        use: {
          loader: 'babel-loader',
          options: {
            presets: [
              ['@babel/preset-env', { targets: "defaults" }, '@babel/preset-react']
            ],
            plugins: ['@babel/plugin-proposal-class-properties']
          }
        }
      }
    ]
  },
  module: {
    parser: {
      javascript: {
        // ...
        commonjsMagicComments: true,
      },
    },
  },
  module: {
    rules: [
      {
        test: /\.css$/i,
        use: ['style-loader', 'css-loader'],
      },
    ],
  },
};

babel.config.json配置 #

{
  "presets": [
    [
      "@babel/preset-env",
      {
        "targets": {
          "edge": "17",
          "firefox": "60",
          "chrome": "67",
          "safari": "11.1"
        },
        "useBuiltIns": "usage",
        "corejs": "3.6.5"
      }
    ],
    [
      "@babel/preset-react",
      {
        "pragma": "dom", // default pragma is React.createElement (only in classic runtime)
        "pragmaFrag": "DomFrag", // default is React.Fragment (only in classic runtime)
        "throwIfNamespace": false, // defaults to true
        "runtime": "classic" // defaults to classic
        // "importSource": "custom-jsx-library" // defaults to react (only in automatic runtime)
      }
    ]
  ]
}

备注 #

• 移除index.js中的JSX代码后，项目可正常构建
• 已查阅相关官方文档并尝试调整core-js版本、清理缓存等操作

1. 修复webpack.config.js的重复module字段问题 #

你在webpack配置里重复定义了三次module对象，后面的配置会直接覆盖前面的，导致原本处理JS的babel-loader规则被最后一个CSS规则覆盖，JSX代码根本没被babel处理。

修改后的webpack.config.js需合并所有module配置到一个对象：

const path = require('path');

module.exports = {
  mode: 'production',
  entry: './src/index.js',
  output: {
    filename: 'main.js',
    path: path.resolve(__dirname, 'dist'),
  },
  module: {
    parser: {
      javascript: {
        commonjsMagicComments: true,
      },
    },
    rules: [
      // 优先处理JS/JSX文件
      {
        test: /\.(?:js|mjs|cjs|jsx)$/, // 新增jsx后缀匹配
        exclude: [
          /node_modules[\\/]core-js/,
          /node_modules[\\/]webpack[\\/]buildin/,
        ],
        use: 'babel-loader' // 直接使用babel.config.json的全局配置，避免冲突
      },
      // 处理CSS文件
      {
        test: /\.css$/i,
        use: ['style-loader', 'css-loader'],
      },
    ]
  },
};

2. 修正babel的React预设配置 #

你的babel.config.json里把React的pragma改成了dom，但代码里还是依赖默认的React.createElement转换JSX，会导致转换后的代码找不到dom函数。删除自定义pragma，恢复默认配置：

{
  "presets": [
    [
      "@babel/preset-env",
      {
        "targets": {
          "edge": "17",
          "firefox": "60",
          "chrome": "67",
          "safari": "11.1"
        },
        "useBuiltIns": "usage",
        "corejs": "3.30.0" // 与安装的core-js版本保持一致
      }
    ],
    [
      "@babel/preset-react",
      {
        "throwIfNamespace": false,
        "runtime": "classic"
      }
    ]
  ]
}

3. 适配React 18的渲染写法（可选） #

你使用的是React 18，建议替换旧的ReactDOM.render为新版API：

import React from 'react';
import ReactDOM from 'react-dom/client';

const root = ReactDOM.createRoot(document.getElementById('root'));
root.render(<h1>Hello World</h1>);

4. 重新构建验证 #

执行npx webpack重新构建项目，即可正常识别JSX语法。

内容的提问来源于stack exchange，提问作者user21597236