通过chrome调试

node --inspect-brk ./node_modules/webpack-cli/bin/cli.js

通过执行命令调试

• 打开工程目录，点击调试按钮，再点击小齿轮的配置按钮系统就会生成 launch.json 配置文件
• 修改好了以后直接点击 F5 就可以启动调试

.vscode\launch.json

{
  "version": "0.2.0",
  "configurations": [
    {
      "type": "node",
      "request": "launch",
      "name": "debug webpack",
      "cwd": "${workspaceFolder}",
      "program": "${workspaceFolder}/node_modules/webpack-cli/bin/cli.js"
    }
  ]
}

debugger.js

const webpack = require("webpack");
const webpackOptions = require("./webpack.config");
const compiler = webpack(webpackOptions);
//4.执行对象的run方法开始执行编译
compiler.run((err, stats) => {
    console.log(err);
    console.log(stats.toJson(
        {
            assets: true,
            chunks: true,
            modules: true,
            entries: true,
        }
    ));
});

调试webpack-cli源码

git clone https://github.com/webpack/webpack.git
git reset --hard vx.x.x
yarn 
yarn link
git clone https://github.com/webpack/webpack-cli.git
git reset --hard webpack-cli@x.x.x
cd packages\webpack-cli
yarn link webpack
yarn link

yarn link webpack
yarn link webpack-cli
yarn unlink webpack
yarn unlink webpack-cli