Webpack中的观察模式，开发服务与HMR等（未完成）
观察模式
webpack-dev-middleware
webpack-dev-server
HMR
参考
- Webpack如何实现万物皆可import？loader的使用/配置/手写实践
https://jzplp.github.io/2026/webpack-loader.html - 理解Webpack插件机制：从插件使用、各类编译对象、Tapable到自定义插件与钩子开发
https://jzplp.github.io/2026/webpack-plugin.html - Webpack GitHub
https://github.com/webpack/webpack - Webpack 文档
https://webpack.js.org/ - Webpack 中文文档
https://webpack.docschina.org/ - Webpack 开发环境
https://webpack.docschina.org/guides/development/ - Webpack 模块热替换
https://webpack.docschina.org/guides/hot-module-replacement/ - Webpack 模块热替换(hot module replacement)
https://webpack.docschina.org/concepts/hot-module-replacement/ - Webpack Hot Module Replacement
https://webpack.docschina.org/api/hot-module-replacement/ - webpack-dev-server GitHub
https://github.com/webpack/webpack-dev-server - webpack-dev-middleware GitHub
https://github.com/webpack/webpack-dev-middleware - Webpack DevServer
https://webpack.docschina.org/configuration/dev-server/