fix: fix css output location for relative baseUrl + more details in docs

Author: yyx990803

docs/config/README.md

@@ -34,9 +34,19 @@ module.exports = {
 - Type: `string`
 - Default: `'/'`
 
-  The base URL your application will be deployed at. By default Vue CLI assumes your app will be deployed at the root of a domain, e.g. `https://www.my-app.com/`. If your app is deployed at a sub-path, you will need to specify that sub-path using this option. For example, if your app is deployed at `https://www.foobar.com/my-app/`, set `baseUrl` to `'/my-app/'`.
+  The base URL your application bundle will be deployed at. This is the equivalent of webpack's `output.publicPath`, but Vue CLI also needs this value for other purposes, so you should **always use `baseUrl` instead of modifying webpack `output.publicPath`**.
 
-  Setting this value correctly is necessary for your static assets to be loaded properly in production.
+  By default, Vue CLI assumes your app will be deployed at the root of a domain, e.g. `https://www.my-app.com/`. If your app is deployed at a sub-path, you will need to specify that sub-path using this option. For example, if your app is deployed at `https://www.foobar.com/my-app/`, set `baseUrl` to `'/my-app/'`.
+
+  The value can also be set to an empty string (`''`) or a relative path (`./`) so that all assets are linked using relative paths. This allows the built bundle to be deployed under any public path, or used in a file system based environment like a Cordova hybrid app.
+
+  ::: warning Limitations of relative baseUrl
+  Relative `baseUrl` has some limitations and should be avoided when:
+
+  - You are using HTML5 `history.pushState` routing;
+
+  - You are using the `pages` option to build a multi-paged app.
+  :::
 
   This value is also respected during development. If you want your dev server to be served at root instead, you can use a conditional value:
 
@@ -48,12 +58,6 @@ module.exports = {
   }
   ```
 
-  The value can also be set to an empty string (`''`) so that all assets are linked using relative paths, so that the bundle can be used in a file system based environment like a Cordova hybrid app. **Note that this will force the generated CSS files to always be placed at the root of the output directory to ensure urls in your CSS work correctly.**
-
-  ::: tip
-  Always use `baseUrl` instead of modifying webpack `output.publicPath`.
-  :::
-
 ### outputDir
 
 - Type: `string`

docs/guide/deployment.md

@@ -8,7 +8,7 @@ If you are developing your frontend app separately from your backend - i.e. your
 
 ### Previewing Locally
 
-The `dist` directory is meant to be served by an HTTP server, so it will not work if you open `dist/index.html` directly over `file://` protocol. The easiest way to preview your production build locally is using a Node.js static file server, for example [serve](https://github.com/zeit/serve):
+The `dist` directory is meant to be served by an HTTP server (unless you've configured `baseUrl` to be a relative value), so it will not work if you open `dist/index.html` directly over `file://` protocol. The easiest way to preview your production build locally is using a Node.js static file server, for example [serve](https://github.com/zeit/serve):
 
 ``` bash
 npm install -g serve

docs/zh/config/README.md

@@ -32,9 +32,19 @@ module.exports = {
 - Type: `string`
 - Default: `'/'`
 
-  部署应用时的基本 URL。默认情况下，Vue CLI 会假设你的应用是被部署在一个域名的根路径上，例如 `https://www.my-app.com/`。如果应用被部署在一个子路径上，你就需要用这个选项指定这个子路径。例如，如果你的应用被部署在 `https://www.my-app.com/my-app/`，则设置 `baseUrl` 为 `/my-app/`。
+  部署应用时的基本 URL。用法和 webpack 本身的 `output.publicPath` 一致，但是 Vue CLI 在一些其他地方也需要用到这个值，所以**请始终使用 `baseUrl` 而不要直接修改 webpack 的 `output.publicPath`**。
 
-  你必须正确地设置这个值以使生产环境中静态资源加载正确。
+  默认情况下，Vue CLI 会假设你的应用是被部署在一个域名的根路径上，例如 `https://www.my-app.com/`。如果应用被部署在一个子路径上，你就需要用这个选项指定这个子路径。例如，如果你的应用被部署在 `https://www.my-app.com/my-app/`，则设置 `baseUrl` 为 `/my-app/`。
+
+  这个值也可以被设置为空字符串 (`''`) 或是相对路径 (`'./'`)，这样所有的资源都会被链接为相对路径，这样打出来的包可以被部署在任意路径，也可以用在类似 Cordova hybrid 应用的文件系统中。
+
+  ::: warning 相对 baseUrl 的限制
+  相对路径的 `baseUrl` 有一些使用上的限制。在以下情况下，应当避免使用相对 `baseUrl`:
+
+  - 当使用基于 HTML5 `history.pushState` 的路由时；
+
+  - 当使用 `pages` 选项构建多页面应用时。
+  :::
 
   这个值在开发环境下同样生效。如果你想把开发服务器架设在根路径，你可以使用一个条件式的值：
 
@@ -46,12 +56,6 @@ module.exports = {
   }
   ```
 
-  这个值也可以被设置为空字符串 (`''`) 这样所有的资源都会被链接为相对路径，这样打出来的包可以用在类似 Cordova hybrid 应用的文件系统中。**注意：生成的 CSS 文件要始终放在输出路径的根部，以确保 CSS 中的 URL 正常工作。**
-
-  ::: tip 提示
-  请始终使用 `baseUrl` 而不要修改 webpack 的 `output.publicPath`。
-  :::
-
 ### outputDir
 
 - Type: `string`

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

@@ -175,7 +175,6 @@ async function build (args, api, options) {
   }
 
   return new Promise((resolve, reject) => {
-    const isFreshBuild = !fs.existsSync(api.resolve('node_modules/.cache'))
     webpack(webpackConfig, (err, stats) => {
       stopSpinner(false)
       if (err) {
@@ -199,17 +198,6 @@ async function build (args, api, options) {
           } else {
             done(`Build complete. Watching for changes...`)
           }
-          if (
-            options.baseUrl === '/' &&
-            // only log the tips if this is the first build
-            isFreshBuild
-          ) {
-            console.log(
-              chalk.gray(`Tip: the directory is meant to be served by an HTTP server, and will not work if\n` +
-              `you open it directly over file:// protocol. To preview it locally, use an HTTP\n` +
-              `server like the ${chalk.yellow(`serve`)} package on npm.\n`)
-            )
-          }
         }
       }
 

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

@@ -25,14 +25,21 @@ module.exports = (api, options) => {
     const shouldExtract = extract !== false && !shadowMode
     const filename = getAssetPath(
       options,
-      `css/[name]${options.filenameHashing ? '.[contenthash:8]' : ''}.css`,
-      true /* placeAtRootIfRelative */
+      `css/[name]${options.filenameHashing ? '.[contenthash:8]' : ''}.css`
     )
     const extractOptions = Object.assign({
       filename,
       chunkFilename: filename
     }, extract && typeof extract === 'object' ? extract : {})
 
+    // use relative publicPath in extracted CSS based on extract location
+    const cssPublicPath = '../'.repeat(
+      extractOptions.filename
+        .replace(/^\.[\/\\]/, '')
+        .split(/[\/\\]/g)
+        .length - 1
+    )
+
     // check if the project has a valid postcss config
     // if it doesn't, don't use postcss-loader for direct style imports
     // because otherwise it would throw error when attempting to load postcss config
@@ -68,6 +75,9 @@ module.exports = (api, options) => {
           rule
             .use('extract-css-loader')
             .loader(require('mini-css-extract-plugin').loader)
+            .options({
+              publicPath: cssPublicPath
+            })
         } else {
           rule
             .use('vue-style-loader')

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

@@ -1,15 +1,6 @@
 const path = require('path')
 
 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 &&
-    !(/^https?:/.test(options.baseUrl)) &&
-    options.baseUrl.charAt(0) !== '/'
-  ) {
-    return filePath.replace(/^\w+\//, '')
-  }
   return options.assetsDir
     ? path.posix.join(options.assetsDir, filePath)
     : filePath