feat: allow using relative baseUrl

packages/@vue/cli-service/lib/Service.js

@@ -248,6 +248,7 @@ module.exports = class Service {
     }
 
     // normlaize some options
+    resolved.baseUrl = resolved.baseUrl.replace(/^\.\//, '')
     ensureSlash(resolved, 'baseUrl')
     removeSlash(resolved, 'outputDir')
 

packages/@vue/cli-service/lib/config/css.js

@@ -24,9 +24,14 @@ module.exports = (api, options) => {
     const shadowMode = !!process.env.VUE_CLI_CSS_SHADOW_MODE
     const isProd = process.env.NODE_ENV === 'production'
     const shouldExtract = isProd && extract !== false && !shadowMode
+    const filename = getAssetPath(
+      options,
+      `css/[name].[contenthash:8].css`,
+      true /* placeAtRootIfRelative */
+    )
     const extractOptions = Object.assign({
-      filename: getAssetPath(options, `css/[name].[contenthash:8].css`),
-      chunkFilename: getAssetPath(options, 'css/[name].[contenthash:8].css')
+      filename,
+      chunkFilename: filename
     }, extract && typeof extract === 'object' ? extract : {})
 
     // check if the project has a valid postcss config

packages/@vue/cli-service/lib/config/prod.js

@@ -2,13 +2,18 @@ module.exports = (api, options) => {
   api.chainWebpack(webpackConfig => {
     if (process.env.NODE_ENV === 'production') {
       const getAssetPath = require('../util/getAssetPath')
+      const filename = getAssetPath(
+        options,
+        `js/[name].[chunkhash:8].js`,
+        true /* placeAtRootIfRelative */
+      )
 
       webpackConfig
         .mode('production')
         .devtool('source-map')
         .output
-          .filename(getAssetPath(options, `js/[name].[chunkhash:8].js`))
-          .chunkFilename(getAssetPath(options, `js/[name].[chunkhash:8].js`))
+          .filename(filename)
+          .chunkFilename(filename)
 
       // keep module.id stable when vendor modules does not change
       webpackConfig

packages/@vue/cli-service/lib/options.js

@@ -1,7 +1,7 @@
 const { createSchema, validate } = require('@vue/cli-shared-utils')
 
 const schema = createSchema(joi => joi.object({
-  baseUrl: joi.string(),
+  baseUrl: joi.string().allow(''),
   outputDir: joi.string(),
   assetsDir: joi.string(),
   runtimeCompiler: joi.boolean(),

packages/@vue/cli-service/lib/util/getAssetPath.js

@@ -1,6 +1,11 @@
 const path = require('path')
 
-module.exports = function getAssetPath (options, filePath) {
+module.exports = function getAssetPath (options, filePath, placeAtRootIfRelative) {
+  // if the user is using a relative URL, place js & css at dist root to ensure
+  // relative paths work properly
+  if (placeAtRootIfRelative && options.baseUrl.charAt(0) !== '/') {
+    return filePath.replace(/^\w+\//, '')
+  }
   return options.assetsDir
     ? path.posix.join(options.assetsDir, filePath)
     : filePath