feat: base without trailing slash

packages/vite/src/node/build.ts

@@ -1124,7 +1124,7 @@ export function toOutputFilePathWithoutRuntime(
   if (relative && !config.build.ssr) {
     return toRelative(filename, hostId)
   } else {
-    return config.base + filename
+    return joinUrlSegments(config.base, filename)
   }
 }
 

packages/vite/src/node/config.ts

@@ -827,14 +827,6 @@ export function resolveBaseUrl(
     }
   }
 
-  // ensure ending slash
-  if (!base.endsWith('/')) {
-    logger.warn(
-      colors.yellow(colors.bold(`(!) "base" option should end with a slash.`))
-    )
-    base += '/'
-  }
-
   return base
 }
 

packages/vite/src/node/plugins/importAnalysis.ts

@@ -34,10 +34,12 @@ import {
   isDataUrl,
   isExternalUrl,
   isJSRequest,
+  joinUrlSegments,
   moduleListContains,
   normalizePath,
   prettifyUrl,
   removeImportQuery,
+  stripBase,
   stripBomTag,
   timeFrom,
   transformStableResult,
@@ -377,7 +379,7 @@ export function importAnalysisPlugin(config: ResolvedConfig): Plugin {
           }
 
           // prepend base (dev base is guaranteed to have ending slash)
-          url = base + url.replace(/^\//, '')
+          url = joinUrlSegments(base, url.replace(/^\//, ''))
         }
 
         return [url, resolved.id]
@@ -538,7 +540,7 @@ export function importAnalysisPlugin(config: ResolvedConfig): Plugin {
 
           // record for HMR import chain analysis
           // make sure to unwrap and normalize away base
-          const hmrUrl = unwrapId(url.replace(base, '/'))
+          const hmrUrl = unwrapId(stripBase(url, base))
           importedUrls.add(hmrUrl)
 
           if (enablePartialAccept && importedBindings) {

packages/vite/src/node/server/middlewares/base.ts

@@ -1,24 +1,22 @@
 import type { Connect } from 'dep-types/connect'
 import type { ViteDevServer } from '..'
-import { joinUrlSegments } from '../../utils'
+import { joinUrlSegments, stripBase } from '../../utils'
 
 // this middleware is only active when (config.base !== '/')
 
 export function baseMiddleware({
   config
 }: ViteDevServer): Connect.NextHandleFunction {
-  const devBase = config.base.endsWith('/') ? config.base : config.base + '/'
-
   // Keep the named function. The name is visible in debug logs via `DEBUG=connect:dispatcher ...`
   return function viteBaseMiddleware(req, res, next) {
     const url = req.url!
     const parsed = new URL(url, 'http://vitejs.dev')
     const path = parsed.pathname || '/'
 
-    if (path.startsWith(devBase)) {
+    if (path.startsWith(config.base)) {
       // rewrite url to remove base. this ensures that other middleware does
       // not need to consider base being prepended or not
-      req.url = url.replace(devBase, '/')
+      req.url = stripBase(url, config.base)
       return next()
     }
 
@@ -36,7 +34,10 @@ export function baseMiddleware({
       return
     } else if (req.headers.accept?.includes('text/html')) {
       // non-based page visit
-      const redirectPath = joinUrlSegments(config.base, url)
+      const redirectPath =
+        url + '/' !== config.base
+          ? joinUrlSegments(config.base, url)
+          : config.base
       res.writeHead(404, {
         'Content-Type': 'text/html'
       })

packages/vite/src/node/utils.ts

@@ -1204,3 +1204,9 @@ export function joinUrlSegments(a: string, b: string): string {
   }
   return a + b
 }
+
+export function stripBase(path: string, base: string): string {
+  const devBase = base.endsWith('/') ? base.slice(0, -1) : base
+
+  return path.replace(RegExp(devBase + '/+'), '/')
+}

playground/assets/__tests__/without-trailing-slash/vite.config.js

@@ -0,0 +1 @@
+module.exports = require('../../vite.config-without-trailing-slash')

playground/assets/package.json

@@ -12,6 +12,9 @@
     "preview:relative-base": "vite --config ./vite.config-relative-base.js preview",
     "dev:runtime-base": "vite --config ./vite.config-runtime-base.js dev",
     "build:runtime-base": "vite --config ./vite.config-runtime-base.js build",
-    "preview:runtime-base": "vite --config ./vite.config-runtime-base.js preview"
+    "preview:runtime-base": "vite --config ./vite.config-runtime-base.js preview",
+    "dev:without-trailing-slash": "vite --config ./vite.config-without-trailing-slash.js dev",
+    "build:without-trailing-slash": "vite --config ./vite.config-without-trailing-slash.js build",
+    "preview:without-trailing-slash": "vite --config ./vite.config-without-trailing-slash.js preview"
   }
 }

playground/assets/vite.config-without-trailing-slash.js

@@ -0,0 +1,13 @@
+const baseConfig = require('./vite.config.js')
+
+/**
+ * @type {import('vite').UserConfig}
+ */
+module.exports = {
+  ...baseConfig,
+  base: '/foo', // overwrite the original base: '/foo/'
+  build: {
+    ...baseConfig.build,
+    outDir: 'dist/without-trailing-slash'
+  }
+}