feat: inject styles under shadow root in web component mode

Author: yyx990803

packages/@vue/cli-service/lib/commands/build/entry-web-component.js

@@ -12,10 +12,6 @@ const name = process.env.CUSTOM_ELEMENT_NAME
 // - true: the instance is always kept alive
 const keepAlive = process.env.CUSTOM_ELEMENT_KEEP_ALIVE
 
-// Whether to use Shadow DOM.
-// default: true
-const useShadowDOM = process.env.CUSTOM_ELEMENT_USE_SHADOW_DOM
-
 const options = typeof Component === 'function'
   ? Component.options
   : Component
@@ -30,6 +26,10 @@ const props = Array.isArray(options.props)
   : options.props || {}
 const propsList = Object.keys(props)
 
+// CSS injection function exposed by vue-loader & vue-style-loader
+const styleInjectors = window[options.__shadowInjectId]
+const injectStyle = root => styleInjectors.forEach(inject => inject(root))
+
 // TODO use ES5 syntax
 class CustomElement extends HTMLElement {
   static get observedAttributes () {
@@ -49,21 +49,15 @@ class CustomElement extends HTMLElement {
     })
 
     this._attached = false
-    if (useShadowDOM) {
-      this._shadowRoot = this.attachShadow({ mode: 'open' })
-    }
+    this._shadowRoot = this.attachShadow({ mode: 'open' })
+    injectStyle(this._shadowRoot)
   }
 
   connectedCallback () {
     this._attached = true
     if (!this._wrapper._isMounted) {
       this._wrapper.$mount()
-      const el = this._wrapper.$el
-      if (useShadowDOM) {
-        this._shadowRoot.appendChild(el)
-      } else {
-        this.appendChild(el)
-      }
+      this._shadowRoot.appendChild(this._wrapper.$el)
     }
     this._wrapper._data._active = true
   }

packages/@vue/cli-service/lib/commands/build/index.js

@@ -2,8 +2,7 @@ const defaults = {
   mode: 'production',
   target: 'app',
   entry: 'src/App.vue',
-  keepAlive: false,
-  shadow: true
+  keepAlive: false
 }
 
 module.exports = (api, options) => {
@@ -12,16 +11,19 @@ module.exports = (api, options) => {
     usage: 'vue-cli-service build [options]',
     options: {
       '--mode': `specify env mode (default: ${defaults.mode})`,
+      '--dest': `specify output directory (default: ${options.outputDir})`,
       '--target': `app | lib | web-component (default: ${defaults.target})`,
       '--entry': `entry for lib or web-component (default: ${defaults.entry})`,
       '--name': `name for lib or web-component (default: "name" in package.json or entry filename)`,
-      '--keepAlive': `keep component alive when web-component is detached? (default: ${defaults.keepAlive})`,
-      '--shadow': `use shadow DOM when building as web-component? (default: ${defaults.shadow})`
+      '--keepAlive': `keep component alive when web-component is detached? (default: ${defaults.keepAlive})`
     }
   }, args => {
     for (const key in defaults) {
       if (args[key] == null) args[key] = defaults[key]
     }
+    if (args.dest == null) {
+      args.dest = options.outputDir
+    }
     api.setMode(args.mode)
 
     const chalk = require('chalk')
@@ -43,16 +45,16 @@ module.exports = (api, options) => {
     }
 
     return new Promise((resolve, reject) => {
-      const targetDir = api.resolve(options.outputDir)
+      const targetDir = api.resolve(args.dest)
       rimraf(targetDir, err => {
         if (err) {
           return reject(err)
         }
         let webpackConfig
         if (args.target === 'lib') {
-          webpackConfig = require('./resolveLibConfig')(api, args)
+          webpackConfig = require('./resolveLibConfig')(api, args, options)
         } else if (args.target === 'web-component') {
-          webpackConfig = require('./resolveWebComponentConfig')(api, args)
+          webpackConfig = require('./resolveWebComponentConfig')(api, args, options)
         } else {
           webpackConfig = api.resolveWebpackConfig()
         }
@@ -66,7 +68,7 @@ module.exports = (api, options) => {
             process.stdout.write(stats.toString({
               colors: true,
               modules: false,
-              children: api.hasPlugin('typescript'),
+              children: api.hasPlugin('typescript') || args.target !== 'app',
               chunks: false,
               chunkModules: false
             }) + '\n\n')

packages/@vue/cli-service/lib/commands/build/resolveLibConfig.js

@@ -1,4 +1,4 @@
-module.exports = (api, { entry, name }) => {
+module.exports = (api, { entry, name, dest }, options) => {
   const libName = name || api.service.pkg.name || entry.replace(/\.(js|vue)$/, '')
   // setting this disables app-only configs
   process.env.VUE_CLI_TARGET = 'lib'
@@ -7,17 +7,20 @@ module.exports = (api, { entry, name }) => {
 
   api.chainWebpack(config => {
     config.output
+      .path(api.resolve(dest))
       .filename(`[name].js`)
       .library(libName)
       .libraryExport('default')
 
     // adjust css output name
-    config
-      .plugin('extract-css')
-        .tap(args => {
-          args[0].filename = `${libName}.css`
-          return args
-        })
+    if (options.css.extract !== false) {
+      config
+        .plugin('extract-css')
+          .tap(args => {
+            args[0].filename = `${libName}.css`
+            return args
+          })
+    }
 
     // only minify min entry
     config

packages/@vue/cli-service/lib/commands/build/resolveWebComponentConfig.js

@@ -1,4 +1,4 @@
-module.exports = (api, { entry, name, keepAlive, shadow }) => {
+module.exports = (api, { entry, name, dest, keepAlive }) => {
   const libName = name || api.service.pkg.name || entry.replace(/\.(js|vue)$/, '')
   if (libName.indexOf('-') < 0) {
     const { log, error } = require('@vue/cli-shared-utils')
@@ -11,19 +11,29 @@ module.exports = (api, { entry, name, keepAlive, shadow }) => {
   process.env.VUE_CLI_TARGET = 'web-component'
   // inline all static asset files since there is no publicPath handling
   process.env.VUE_CLI_INLINE_LIMIT = Infinity
+  // Disable CSS extraction and turn on CSS shadow mode for vue-style-loader
+  process.env.VUE_CLI_CSS_SHADOW_MODE = true
 
   api.chainWebpack(config => {
+    config.entryPoints.clear()
+    // set proxy entry for *.vue files
+    if (/\.vue$/.test(entry)) {
+      config
+          .entry(libName)
+            .add(require.resolve('./entry-web-component.js'))
+      config.resolve
+          .alias
+            .set('~entry', api.resolve(entry))
+    } else {
+      config
+          .entry(libName)
+            .add(api.resolve(entry))
+    }
+
     config.output
+      .path(api.resolve(dest))
       .filename(`[name].js`)
 
-    // only minify min entry
-    config
-      .plugin('uglify')
-        .tap(args => {
-          args[0].include = /\.min\.js$/
-          return args
-        })
-
     // externalize Vue in case user imports it
     config
       .externals({
@@ -35,37 +45,19 @@ module.exports = (api, { entry, name, keepAlive, shadow }) => {
         .use(require('webpack/lib/DefinePlugin'), [{
           'process.env': {
             CUSTOM_ELEMENT_NAME: JSON.stringify(libName),
-            CUSTOM_ELEMENT_KEEP_ALIVE: keepAlive,
-            CUSTOM_ELEMENT_USE_SHADOW_DOM: shadow
+            CUSTOM_ELEMENT_KEEP_ALIVE: keepAlive
           }
         }])
 
-    // TODO handle CSS (insert in shadow DOM)
+    // enable shadow mode in vue-loader
+    config.module
+      .rule('vue')
+        .use('vue-loader')
+          .tap(options => {
+            options.shadowMode = true
+            return options
+          })
   })
 
-  function genConfig (postfix) {
-    postfix = postfix ? `.${postfix}` : ``
-    api.chainWebpack(config => {
-      config.entryPoints.clear()
-      // set proxy entry for *.vue files
-      if (/\.vue$/.test(entry)) {
-        config
-          .entry(`${libName}${postfix}`)
-            .add(require.resolve('./entry-web-component.js'))
-        config.resolve
-          .alias
-            .set('~entry', api.resolve(entry))
-      } else {
-        config
-          .entry(`${libName}${postfix}`)
-            .add(api.resolve(entry))
-      }
-    })
-    return api.resolveWebpackConfig()
-  }
-
-  return [
-    genConfig(''),
-    genConfig('min')
-  ]
+  return api.resolveWebpackConfig()
 }

packages/@vue/cli-service/lib/webpack/CSSLoaderResolver.js

@@ -29,7 +29,7 @@ module.exports = class CSSLoaderResolver {
     this.cssLoader = 'css-loader'
     this.fallbackLoader = 'vue-style-loader'
     this.sourceMap = sourceMap
-    this.extract = extract
+    this.extract = extract && !process.env.VUE_CLI_CSS_SHADOW_MODE
     this.minimize = minimize
     this.modules = modules
     this.postcss = postcss
@@ -83,6 +83,7 @@ module.exports = class CSSLoaderResolver {
       }) : [{
         loader: this.fallbackLoader,
         options: {
+          shadowMode: !!process.env.VUE_CLI_CSS_SHADOW_MODE,
           sourceMap: this.sourceMap
         }
       }, ...use]

packages/@vue/cli-service/package.json

@@ -55,7 +55,7 @@
     "thread-loader": "^1.1.2",
     "uglifyjs-webpack-plugin": "^1.1.6",
     "url-loader": "^0.6.2",
-    "vue-loader": "^13.7.0",
+    "vue-loader": "^14.0.0",
     "vue-style-loader": "^3.1.1",
     "vue-template-compiler": "^2.5.13",
     "webpack": "^3.10.0",

packages/@vue/cli/bin/vue.js

@@ -66,8 +66,8 @@ program
   .command('build [entry]')
   .option('-t, --target <target>', 'Build target (app | lib | web-component, default: app)')
   .option('-n, --name <name>', 'name for lib or web-component (default: entry filename)')
+  .option('-d, --dest <dir>', 'output directory (default: dist)')
   .option('--keepAlive', 'keep component alive when web-component is detached? (default: false)')
-  .option('--shadow', 'use shadow DOM when building as web-component? (default: true)')
   .description('build a .js or .vue file in production mode with zero config')
   .action((entry, cmd) => {
     loadCommand('build', '@vue/cli-service-global').build(entry, cleanArgs(cmd))

yarn.lock

@@ -10077,9 +10077,9 @@ vue-jest@^2.0.0:
     tsconfig "^7.0.0"
     vue-template-es2015-compiler "^1.5.3"
 
-vue-loader@^13.7.0:
-  version "13.7.0"
-  resolved "https://registry.yarnpkg.com/vue-loader/-/vue-loader-%3Cspan%20class="x x-first x-last">13.7.0.tgz#4d6a35b169c2a0a488842fb95c85052105fa9729"
+vue-loader@^14.0.0:
+  version "14.0.0"
+  resolved "https://registry.yarnpkg.com/vue-loader/-/vue-loader-%3Cspan%20class="x x-first x-last">14.0.0.tgz#47175b739309b25d3b1f6b48466e72332093f533"
   dependencies:
     consolidate "^0.14.0"
     hash-sum "^1.0.2"
@@ -10092,7 +10092,7 @@ vue-loader@^13.7.0:
     resolve "^1.4.0"
     source-map "^0.6.1"
     vue-hot-reload-api "^2.2.0"
-    vue-style-loader "^3.0.0"
+    vue-style-loader "^4.0.1"
     vue-template-es2015-compiler "^1.6.0"
 
 vue-parser@^1.1.5:
@@ -10112,16 +10112,16 @@ vue-router@^3.0.1:
   version "3.0.1"
   resolved "https://registry.yarnpkg.com/vue-router/-/vue-router-3.0.1.tgz#d9b05ad9c7420ba0f626d6500d693e60092cc1e9"
 
-vue-style-loader@^3.0.0:
-  version "3.0.3"
-  resolved "https://registry.yarnpkg.com/vue-style-loader/-/vue-style-loader-3.%3Cspan%20class="x x-first x-last">0.3.tgz#623658f81506aef9d121cdc113a4f5c9cac32df7"
+vue-style-loader@^3.1.1:
+  version "3.1.1"
+  resolved "https://registry.yarnpkg.com/vue-style-loader/-/vue-style-loader-3.%3Cspan%20class="x x-first x-last">1.1.tgz#74fdef91a81d38bc0125746a1b5505e62d69e32c"
   dependencies:
     hash-sum "^1.0.2"
     loader-utils "^1.0.2"
 
-vue-style-loader@^3.1.1:
-  version "3.1.1"
-  resolved "https://registry.yarnpkg.com/vue-style-loader/-/vue-style-loader-%3Cspan%20class="x x-first x-last">3.1.1.tgz#74fdef91a81d38bc0125746a1b5505e62d69e32c"
+vue-style-loader@^4.0.1:
+  version "4.0.1"
+  resolved "https://registry.yarnpkg.com/vue-style-loader/-/vue-style-loader-%3Cspan%20class="x x-first x-last">4.0.1.tgz#252300d32eb97e83c1a1cb5b2029e2d8c3adcf9f"
   dependencies:
     hash-sum "^1.0.2"
     loader-utils "^1.0.2"