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webpack5教程

yzqdev大约 4 分钟

webpack5教程

热部署

webpack's Watch Mode

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"watch": "webpack --watch"

自动编译模块!!! 唯一的缺点是，为了看到修改后的实际效果，你需要刷新浏览器。如果能够自动刷新浏览器就更好了，可以尝试使用 webpack-dev-server，恰好可以实现我们想要的功能。

webpack-dev-server

"start": "webpack serve --open",

# 配置如下
 const path = require('path');
  const HtmlWebpackPlugin = require('html-webpack-plugin');
  const CleanWebpackPlugin = require('clean-webpack-plugin');

  module.exports = {
    entry: {
      app: './src/index.js',
      print: './src/print.js'
    },
    devtool: 'inline-source-map',
   devServer: {
     contentBase: './dist'
   },
    plugins: [
      new CleanWebpackPlugin(['dist']),
      new HtmlWebpackPlugin({
        title: 'Development'
      })
    ],
    output: {
      filename: '[name].bundle.js',
      path: path.resolve(__dirname, 'dist')
    }
  };

现在，我们可以在命令行中运行 npm start，就会看到浏览器自动加载页面。如果现在修改和保存任意源文件，web 服务器就会自动重新加载编译后的代码。试一下

webpack-dev-middlewara

搭配express进行热部署,地址 webpack配置express

webpack5配置

  1. Error: Cannot find module 'webpack-cli/bin/config-yargs'

在webpack-cli 4.x中，不能过webpack-dev-server启动项目了，需要通过webpack serve...或者修改webpack-cli版本改为3.x

  // package.json
  // webpack4.x
  "script": {
    "dev": "webpack-dev-server ...",
  }
  // webpack5.x
  "script": {
    "dev": "webpack serve ...",
  }
  // 降版本
  {
    webpack-cli@3.3.12
  }
  1. webpack5中错误出现错误UnhandledPromiseRejectionWarning: TypeError: webpack.NamedModulesPlugin is not a constructor
  // webpack.config.js

  // webpack4.x
  module.exports = {
    ...
    plugins: [
      ...
      new webpack.NamedModulesPlugin()
    ]
  }

  // webpack5.x
  // 在webpack5.x中，webpack.NamedModulesPlugin的功能已经内置
  1. babel配置导致的文件引入错误，@babel/runtime

在webpack5.x中，发现很多关于@babel/runtime/helpers/esm的文件引入错误，错误提示类似下面，通过锁定@babel/runtime包版本即可

Module not found: Error: Can't resolve './superPropBase' in '/Users/xxx/node_modules/@babel/runtime/helpers/esm'
Did you mean 'superPropBase.js'?
BREAKING CHANGE: The request './superPropBase' failed to resolve only because it was resolved as fully specified
(probably because the origin is a '*.mjs' file or a '*.js' file where the package.json contains '"type": "module"').
The extension in the request is mandatory for it to be fully specified.
Add the extension to the request
  npm install @babel/runtime@7.12.0 -D
  1. webpack < 5 used to include polyfills for node.js core modules by default

在运行过程中出现了很多这样的报错信息，是由于在webpack5中移除了nodejs核心模块的polyfill自动引入，所以需要手动引入，如果打包过程中有使用到nodejs核心模块，webpack会提示进行相应配置

  // webpack.config.js
  module.exports = {
    ...
    resolve: {
      // https://github.com/babel/babel/issues/8462
      // https://blog.csdn.net/qq_39807732/article/details/110089893
      // 如果确认需要node polyfill，设置resolve.fallback安装对应的依赖
      fallback: {
        crypto: require.resolve('crypto-browserify'),
        path: require.resolve('path-browserify'),
        url: require.resolve('url'),
        buffer: require.resolve('buffer/'),
        util: require.resolve('util/'),
        stream: require.resolve('stream-browserify/'),
        vm: require.resolve('vm-browserify')
      },
      // 如果确认不需要node polyfill，设置resolve.alias设置为false
      alias: {
        crypto: false
      }
    }
  }

如果实在vue-cli中,需要这样

module.exports = {
  configureWebpack: {
    resolve: {
      fallback: {
        path: require.resolve('path-browserify'),
      },
    },
  },

  transpileDependencies: true
}
  1. DeprecationWarning: Compilation.assets will be frozen in future, all modifications are deprecated. BREAKING CHANGE: No more changes should happen to Compilation.assets after sealing the Compilation. Do changes to assets earlier, e. g. in Compilation.hooks.processAssets. Mak`e sure to select an appropriate stage from Compilation.PROCESS_ASSETS_STAGE_*.

为html-webpack-plugin这个包导致的⚠️信息，github issue

  npm run html-webpack-plugin@next -D
  1. DeprecationWarning: A 'callback' argument need to be provided to the 'webpack(options, callback)' function when the 'watch' option is set. There is no way to handle the 'watch' option without a callback

官方给出的问题原因是webpack-cli这个包的版本导致的，github issue

  // 官方提供的解决方式，修改webpack-cli版本到4.2.0既可
  npm install webpack-cli@4.2.0 --save-dev

不过我在本地创建了一个新的项目，版本信息如下，还是存在上面的那个报错信息，demo地址github issue

  "webpack": "^5.10.3",
  "webpack-cli": "^4.2.0",
  "webpack-dev-server": "^3.11.0"
  1. 业务插件遇到的问题，webpack-merge包遇到的问题

csdn资料

  // 4.x版本
  {
    "webpack-merge": "^4.2.2"
  }
  // webpack.config.js
  const merge = require('webpack-merge')
  const defaultConfig = require('../...')
  const config = merge(defaultConfig, {

  })
  export default config

  // 5.x版本
  {
    "webpack-merge": "^5.7.0"
  }
  const webpackMerge = require('webpack-merge')
  const defaultConfig = require('../...')
  const config = webpackMerge.merge(defaultConfig, {

  })
  export default config
  1. 数据流工具recoil好像还不支持在webpack中使用，我们项目里有使用recoil，配置了babel后，一直提示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

官方答复：guthub issue

  1. TypeError: Cannot read property 'tap' of undefined

hard-source-webpack-plugin这个包在版本升级后出现错误，github issue

  // webpack.config.js
  // webpack4.x
  const HardSourceWebpackPlugin = require('hard-source-webpack-plugin')
  module.exports = {
    ...
    piugins: [
      new HardSourceWebpackPlugin({
        environmentHash: {
          root: process.cwd(),
          directories: [],
          files: ['package-lock.json', 'yarn.lock'],
        },
        cachePrune: {
          maxAge: 2 * 24 * 60 * 60 * 1000,
          sizeThreshold: 50 * 1024 * 1024
        }
      })
    ]
  }
  // webpack5.x
  // https://github.com/mzgoddard/hard-source-webpack-plugin/issues/461
  const HardSourceWebpackPlugin = require('hard-source-webpack-plugin')
  module.exports = {
    ...
    piugins: [
      new HardSourceWebpackPlugin(),
      new HardSourceWebpackPlugin.ExcludeModulePlugin([])
    ]
  }