javascript - webpack分别在linux和windows平台打包，同一张CSS背景图不同平台路径不一致？

Question

我的vue项目通过webpack做了一个简单的皮肤切换功能。这个功能只有部分页面包含，做完以后我发现了一个问题。需要皮肤切换的页面，如果是在windows下打包部署的话，会出现CSS背景图的路径错误的问题，但是在linux平台下完全正常。

我这个皮肤功能大致原理就是通过另外增加两个入口文件（blue入口和red入口）来达到blue版的CSS放在blue.css中，red版的CSS放在red.css中，然后通过dom来动态切换这两个文件实现皮肤切换。

打包后正确的CSS背景图片引用路径应该图中所示：
可以看到返回了两个层级的目录。

但是到了windows平台下就变成了这样子：
可以看到没有返回到上两个层级的目录。

而且只有在这个皮肤样式文件中（blue.xxxxx.css和red.xxxxx.css）的背景图才有问题。

我的webpack配置如下：

'use strict'
const path = require('path')
const defaultSettings = require('./src/settings.js')
const webpack = require('webpack')
var HardSourceWebpackPlugin = require('hard-source-webpack-plugin')
// const MiniCssExtractPlugin = require('mini-css-extract-plugin')
// 不要使用自己安装的mini-css-extract-plugin，会报错，使用vue内置的，可能是因为版本不一致的原因
const MiniCssExtractPlugin = require('./node_modules/@vue/cli-service/node_modules/mini-css-extract-plugin')
const htmlWebpackInjectAttributesPlugin = require('html-webpack-inject-attributes-plugin')
const HtmlWebpackExcludeAssetsPlugin = require('html-webpack-exclude-assets-plugin')

// npx vue-cli-service inspect --mode=production >> webpack.config.js  打印生产配置
// npx vue-cli-service inspect --mode=development >> webpack.config.dev.js  打印开发配置

function resolve(dir) {
  return path.join(__dirname, dir)
}

function setPublicPath() {
  return (process.env.ENV === 'production' ? './' : '/udap-web/')
}

function setOutPutDir() {
  let packageName = ''
  if (process.env.ENV === 'staging' || process.env.ENV === 'development') {
    packageName = 'udap-web'
  } else {
    packageName = 'udap'
  }
  return path.resolve(__dirname, packageName)
}

const themeReg = /^(.*)((red|blue)\..+\.css)$/
const themeRegJS = /^(.*)((red|blue).*\.js)$/
const themeLinkJudge = (tagName, attributes) => {
  return (
    tagName === 'link' && attributes.href && themeReg.test(attributes.href)
  )
}

const name = defaultSettings.title || '' // page title

// If your port is set to 80,
// use administrator privileges to execute the command line.
// For example, Mac: sudo npm run
// You can change the port by the following method:
// port = 9527 npm run dev OR npm run dev --port = 9527
const port = process.env.port || process.env.npm_config_port || 9527 // dev port

// All configuration item explanations can be find in https://cli.vuejs.org/config/
module.exports = {
  /**
   * You will need to set publicPath if you plan to deploy your site under a sub path,
   * for example GitHub Pages. If you plan to deploy your site to https://foo.github.io/bar/,
   * then publicPath should be set to "/bar/".
   * In most cases please use '/' !!!
   * Detail: https://cli.vuejs.org/config/#publicpath
   */
  publicPath: setPublicPath(),
  outputDir: setOutPutDir(),
  assetsDir: 'udap-web-assets',
  lintOnSave: process.env.NODE_ENV === 'development',
  productionSourceMap: false,
  devServer: {
    port: port,
    disableHostCheck: true,
    proxy: {
      '/mock-api': {
        target: '/',
        changeOrigin: true
      },
      '/api/udap_web/websocket': {
        target: 'ws://xxx.xxx.xx.xxxx:3000',
        changeOrigin: true,
        pathRewrite: {
          '^/api': ''
        }
      },
      '/api': {
        target: 'http://xxx.xxx.xx.xxxx:3000', // 公司服务器
        changeOrigin: true
      },
      '/cogones-api': {
        target: 'http://xxx.xxx.xx.xxxx:9300',
        changeOrigin: true,
        pathRewrite: {
          '^/cogones-api': ''
        }
      }
    }
  },
  configureWebpack: {
    devtool: 'source-map',
    // provide the app's title in webpack's name field, so that
    // it can be accessed in index.html to inject the correct title.
    name: name,
    resolve: {
      alias: {
        '@': path.resolve(__dirname, 'src')
      }
    },
    plugins: [
      new HardSourceWebpackPlugin(),
      new webpack.ProvidePlugin({ _: 'lodash' })
    ],
    performance: {
      hints: false
    },
    entry: {
      app: path.resolve(__dirname, 'src/main.js'),
      blue: path.resolve(__dirname, 'src/theme/blue/index.js'),
      red: path.resolve(__dirname, 'src/theme/red/index.js')
    }
  },
  chainWebpack(config) {
    // it can improve the speed of the first screen, it is recommended to turn on preload
    // it can improve the speed of the first screen, it is recommended to turn on preload
    config.plugin('preload').tap(() => [
      {
        rel: 'preload',
        // to ignore runtime.js
        // https://github.com/vuejs/vue-cli/blob/dev/packages/@vue/cli-service/lib/config/app.js#L171
        fileBlacklist: [/\.map$/, /hot-update\.js$/, /runtime\..*\.js$/],
        include: 'initial'
      }
    ])

    // when there are many pages, it will cause too many meaningless requests
    config.plugins.delete('prefetch')

    // set svg-sprite-loader
    config.module
      .rule('svg')
      .exclude.add(resolve('src/icons'))
      .end()
    config.module
      .rule('icons')
      .test(/\.svg$/)
      .include.add(resolve('src/icons'))
      .end()
      .use('svg-sprite-loader')
      .loader('svg-sprite-loader')
      .options({
        symbolId: 'icon-[name]'
      })
      .end()

    config
      .when(process.env.NODE_ENV !== 'development',
        config => {
          config
            .plugin('ScriptExtHtmlWebpackPlugin')
            .after('html')
            .use('script-ext-html-webpack-plugin', [{
              // `runtime` must same as runtimeChunk name. default is `runtime`
              inline: /runtime\..*\.js$/
            }])
            .end()

          config
            .optimization.splitChunks({
              chunks: 'all',
              cacheGroups: {
                libs: {
                  name: 'chunk-libs',
                  test: /[\\/]node_modules[\\/]/,
                  priority: 10,
                  chunks: 'initial' // only package third parties that are initially dependent
                },
                elementUI: {
                  name: 'chunk-elementUI', // split elementUI into a single package
                  priority: 20, // the weight needs to be larger than libs and app or it will be packaged into libs or app
                  test: /[\\/]node_modules[\\/]_?element-ui(.*)/ // in order to adapt to cnpm
                },
                commons: {
                  name: 'chunk-commons',
                  test: resolve('src/components'), // can customize your rules
                  minChunks: 3, //  minimum common number
                  priority: 5,
                  reuseExistingChunk: true
                }
              }
            })
          // https:// webpack.js.org/configuration/optimization/#optimizationruntimechunk
          config.optimization.runtimeChunk('single')
        }
      )

    /** 皮肤配置  start */
    // MiniCssExtractPlugin可以给不同入口的独立打包css文件
    // dev环境下vue使用的不是MiniCssExtractPlugin来提取css生成css文件，而是使用vue-style-loader来生成style标签，
    // 因为我们需要生成文件，所以这里即使dev环境下也使用MiniCssExtractPlugin

    config.when(process.env.NODE_ENV === 'development', config => {
      config
        .plugin('extract-css')
        .use(MiniCssExtractPlugin, [
          {
            filename: '[name].[contenthash:8].css',
            chunkFilename: '[name].[contenthash:8].css'
          }
        ])
        .end()
    })

    // 让normal这个module不去匹配我们的主题文件  /^((?!light\.scss|default\.scss).)*$/
    config.module
      .rule('scss')
      .oneOf('normal')
      .test((p1) => {
        const pat = /^(?!.*\\theme\\).*\.scss$/
        const result = pat.test(p1)
        return result
      })
      .end()

    // 定义自己的module来使用我们自己的loader .*(light|default)\.scss$
    const theme = config.module
      .rule('scss')
      .oneOf('ownTheme')
      .test(/^(?=.*\\theme\\).*\.scss$/)
    // 清除vue-cli写好的loader,改用自己写的
    theme.uses.clear()

    theme
      .use(MiniCssExtractPlugin.loader)
      .loader(MiniCssExtractPlugin.loader)
      .end()
      .use('css-loader')
      .loader('css-loader')
      .end()
      .use('postcss-loader')
      .loader('postcss-loader')
      .end()
      .use('sass-loader')
      .loader('sass-loader')
      .end()

    // 增加自定义标签属性
    config
      .plugin('html')
      .tap((args) => {
        args[0].attributes = {
          'data-theme': function(tag) {
            const { attributes, tagName } = tag
            if (themeLinkJudge(tagName, attributes)) {
              return 'true'
            }
            return false
          },
          rel: function(tag) {
            const { attributes, tagName } = tag
            if (themeLinkJudge(tagName, attributes)) {
              if (attributes.href.indexOf('blue') > -1) {
                return 'stylesheet'
              }
              return 'alternate stylesheet'
            } else if (tagName === 'link') {
              return 'stylesheet'
            }
            return false
          },
          title: function(tag) {
            const { attributes, tagName } = tag
            if (themeLinkJudge(tagName, attributes)) {
              if (attributes.href.indexOf('red') > -1) {
                return 'red'
              } else if (attributes.href.indexOf('blue') > -1) {
                return 'blue'
              }
              return false
            }
            return false
          }
        }

        args[0].excludeAssets = [themeRegJS]
        return args
      })
      .end()

    // HtmlWebpackPlugin生成HTML文件时，这个插件能给生成的标签注入自己需要的属性
    config
      .plugin('htmlInjectAttribute')
      .after('html')
      .use(htmlWebpackInjectAttributesPlugin)
      .end()

    // 移除多入口生成的无用script标签和JS文件
    config
      .plugin('ExcludeAssets')
      .after('htmlInjectAttribute')
      .use(HtmlWebpackExcludeAssetsPlugin)
      .end()

    /** 皮肤配置 end */
  }
}

我的scss代码如图所示：

Answer 1

经过本人的排查，我发现为皮肤定义的webpack config.module中的MiniCssExtractPlugin.loader和vue-cli定义MiniCssExtractPlugin.loader存在差异，
vue-cli中的配置如下：

rule
.use('extract-css-loader')
.loader(require('mini-css-extract-plugin').loader)
.options({
  hmr: !isProd,
  publicPath: cssPublicPath
})

vue-cli源码中的MiniCssExtractPlugin.loader多了publicPath，所以根据实际情况我也定义了一个适合自己项目的publicPath，至此就顺利解决了这个问题。