feat: add Nitro event handler

Author: userquin

package.json

@@ -62,6 +62,11 @@
     "vitest": "^2.1.1",
     "vue-tsc": "^2.1.6"
   },
+  "build": {
+    "externals": [
+      "defu"
+    ]
+  },
   "stackblitz": {
     "installDependencies": false,
     "startCommand": "pnpm install && pnpm dev:prepare && pnpm dev"

playground/nuxt.config.ts

@@ -14,6 +14,7 @@ export default defineNuxtConfig({
       viewportSize: true,
       prefersColorScheme: true,
     },
+    serverImages: true,
   },
 
 })

src/runtime/plugins/critical.server.ts

@@ -1,40 +1,11 @@
-import type { Browser, parseUserAgent } from 'detect-browser-es'
-import type {
-  ResolvedHttpClientHintsOptions,
-  CriticalInfo,
-  CriticalClientHintsConfiguration,
-} from '../shared-types/types'
+import type { parseUserAgent } from 'detect-browser-es'
+import { CriticalHintsHeaders, extractCriticalHints } from '../utils/critical'
+import type { ResolvedHttpClientHintsOptions } from '../shared-types/types'
 import { useHttpClientHintsState } from './state'
-import { lookupHeader, writeClientHintHeaders, writeHeaders } from './headers'
-import { browserFeatureAvailable } from './features'
-import {
-  defineNuxtPlugin,
-  useCookie,
-  useRuntimeConfig,
-  useRequestHeaders,
-} from '#imports'
+import { writeHeaders } from './headers'
+import { defineNuxtPlugin, useCookie, useRequestHeaders, useRuntimeConfig } from '#imports'
 import type { Plugin } from '#app'
 
-const AcceptClientHintsHeaders = {
-  prefersColorScheme: 'Sec-CH-Prefers-Color-Scheme',
-  prefersReducedMotion: 'Sec-CH-Prefers-Reduced-Motion',
-  prefersReducedTransparency: 'Sec-CH-Prefers-Reduced-Transparency',
-  viewportHeight: 'Sec-CH-Viewport-Height',
-  viewportWidth: 'Sec-CH-Viewport-Width',
-  width: 'Sec-CH-Width',
-  devicePixelRatio: 'Sec-CH-DPR',
-}
-
-type AcceptClientHintsHeadersKey = keyof typeof AcceptClientHintsHeaders
-
-const AcceptClientHintsRequestHeaders = Object.entries(AcceptClientHintsHeaders).reduce((acc, [key, value]) => {
-  acc[key as AcceptClientHintsHeadersKey] = value.toLowerCase() as Lowercase<string>
-  return acc
-}, {} as Record<AcceptClientHintsHeadersKey, Lowercase<string>>)
-
-const SecChUaMobile = 'Sec-CH-UA-Mobile'.toLowerCase() as Lowercase<string>
-const HttpRequestHeaders = Array.from(Object.values(AcceptClientHintsRequestHeaders)).concat('user-agent', 'cookie', SecChUaMobile)
-
 const plugin: Plugin = defineNuxtPlugin({
   name: 'http-client-hints:critical-server:plugin',
   enforce: 'pre',
@@ -44,303 +15,22 @@ const plugin: Plugin = defineNuxtPlugin({
   async setup(nuxtApp) {
     const state = useHttpClientHintsState()
     const httpClientHints = useRuntimeConfig().public.httpClientHints as ResolvedHttpClientHintsOptions
-    const requestHeaders = useRequestHeaders<string>(HttpRequestHeaders)
-
-    // 1. extract browser info
+    const requestHeaders = useRequestHeaders<string>(CriticalHintsHeaders)
     const userAgent = nuxtApp.ssrContext?._httpClientHintsUserAgent as ReturnType<typeof parseUserAgent>
-    // 2. prepare client hints request
-    const clientHintsRequest = collectClientHints(userAgent, httpClientHints.critical!, requestHeaders)
-    // 3. write client hints response headers
-    writeClientHintsResponseHeaders(clientHintsRequest, httpClientHints.critical!)
-    state.value.critical = clientHintsRequest
-    // 4. send the theme cookie to the client when required
-    state.value.critical.colorSchemeCookie = writeThemeCookie(
-      clientHintsRequest,
-      httpClientHints.critical!,
+    state.value.critical = extractCriticalHints(
+      httpClientHints,
+      requestHeaders,
+      userAgent,
+      writeHeaders,
+      (cookieName, path, expires, themeName) => {
+        useCookie(cookieName, {
+          path,
+          expires,
+          sameSite: 'lax',
+        }).value = themeName
+      },
     )
   },
 })
 
 export default plugin
-
-type BrowserFeatureAvailable = (android: boolean, versions: number[]) => boolean
-type BrowserFeatures = Record<AcceptClientHintsHeadersKey, BrowserFeatureAvailable>
-
-// Tests for Browser compatibility
-// https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Sec-CH-Prefers-Reduced-Motion#browser_compatibility
-// https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Sec-CH-Prefers-Reduced-Transparency
-// https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Sec-CH-Prefers-Color-Scheme#browser_compatibility
-// https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/DPR#browser_compatibility
-const chromiumBasedBrowserFeatures: BrowserFeatures = {
-  prefersColorScheme: (_, v) => v[0] >= 93,
-  prefersReducedMotion: (_, v) => v[0] >= 108,
-  prefersReducedTransparency: (_, v) => v[0] >= 119,
-  viewportHeight: (_, v) => v[0] >= 108,
-  viewportWidth: (_, v) => v[0] >= 108,
-  // TODO: check if this is correct, no entry in mozilla docs, using DPR
-  width: (_, v) => v[0] >= 46,
-  devicePixelRatio: (_, v) => v[0] >= 46,
-}
-const allowedBrowsers: [browser: Browser, features: BrowserFeatures][] = [
-  // 'edge',
-  // 'edge-ios',
-  ['chrome', chromiumBasedBrowserFeatures],
-  ['edge-chromium', {
-    ...chromiumBasedBrowserFeatures,
-    devicePixelRatio: (_, v) => v[0] >= 79,
-  }],
-  ['chromium-webview', chromiumBasedBrowserFeatures],
-  ['opera', {
-    prefersColorScheme: (android, v) => v[0] >= (android ? 66 : 79),
-    prefersReducedMotion: (android, v) => v[0] >= (android ? 73 : 94),
-    prefersReducedTransparency: (_, v) => v[0] >= 79,
-    viewportHeight: (android, v) => v[0] >= (android ? 73 : 94),
-    viewportWidth: (android, v) => v[0] >= (android ? 73 : 94),
-    // TODO: check if this is correct, no entry in mozilla docs, using DPR
-    width: (_, v) => v[0] >= 33,
-    devicePixelRatio: (_, v) => v[0] >= 33,
-  }],
-]
-
-const ClientHeaders = ['Accept-CH', 'Vary', 'Critical-CH']
-
-function lookupClientHints(
-  userAgent: ReturnType<typeof parseUserAgent>,
-  criticalClientHintsConfiguration: CriticalClientHintsConfiguration,
-  headers: { [key in Lowercase<string>]?: string | undefined },
-) {
-  const features: CriticalInfo = {
-    firstRequest: true,
-    prefersColorSchemeAvailable: false,
-    prefersReducedMotionAvailable: false,
-    prefersReducedTransparencyAvailable: false,
-    viewportHeightAvailable: false,
-    viewportWidthAvailable: false,
-    widthAvailable: false,
-    devicePixelRatioAvailable: false,
-  }
-
-  if (userAgent == null || userAgent.type !== 'browser')
-    return features
-
-  if (criticalClientHintsConfiguration.prefersColorScheme)
-    features.prefersColorSchemeAvailable = browserFeatureAvailable(allowedBrowsers, userAgent, 'prefersColorScheme')
-
-  if (criticalClientHintsConfiguration.prefersReducedMotion)
-    features.prefersReducedMotionAvailable = browserFeatureAvailable(allowedBrowsers, userAgent, 'prefersReducedMotion')
-
-  if (criticalClientHintsConfiguration.prefersReducedTransparency)
-    features.prefersReducedMotionAvailable = browserFeatureAvailable(allowedBrowsers, userAgent, 'prefersReducedTransparency')
-
-  if (criticalClientHintsConfiguration.viewportSize) {
-    features.viewportHeightAvailable = browserFeatureAvailable(allowedBrowsers, userAgent, 'viewportHeight')
-    features.viewportWidthAvailable = browserFeatureAvailable(allowedBrowsers, userAgent, 'viewportWidth')
-  }
-
-  if (criticalClientHintsConfiguration.width) {
-    features.widthAvailable = browserFeatureAvailable(allowedBrowsers, userAgent, 'width')
-  }
-
-  if (features.viewportWidthAvailable || features.viewportHeightAvailable) {
-    // We don't need to include DPR on desktop browsers.
-    // Since sec-ch-ua-mobile is a low entropy header, we don't need to include it in Accept-CH,
-    // the user agent will send it always unless blocked by a user agent permission policy, check:
-    // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Sec-CH-UA-Mobile
-    const mobileHeader = lookupHeader(
-      'boolean',
-      SecChUaMobile,
-      headers,
-    )
-    if (mobileHeader)
-      features.devicePixelRatioAvailable = browserFeatureAvailable(allowedBrowsers, userAgent, 'devicePixelRatio')
-  }
-
-  return features
-}
-
-function collectClientHints(
-  userAgent: ReturnType<typeof parseUserAgent>,
-  criticalClientHintsConfiguration: CriticalClientHintsConfiguration,
-  headers: { [key in Lowercase<string>]?: string | undefined },
-) {
-  // collect client hints
-  const hints = lookupClientHints(userAgent, criticalClientHintsConfiguration, headers)
-
-  if (criticalClientHintsConfiguration.prefersColorScheme) {
-    if (criticalClientHintsConfiguration.prefersColorSchemeOptions) {
-      const cookieName = criticalClientHintsConfiguration.prefersColorSchemeOptions.cookieName
-      const cookieValue = headers.cookie?.split(';').find(c => c.trim().startsWith(`${cookieName}=`))
-      if (cookieValue) {
-        const value = cookieValue.split('=')?.[1].trim()
-        if (criticalClientHintsConfiguration.prefersColorSchemeOptions.themeNames.includes(value)) {
-          hints.colorSchemeFromCookie = value
-          hints.firstRequest = false
-        }
-      }
-    }
-    if (!hints.colorSchemeFromCookie) {
-      const value = hints.prefersColorSchemeAvailable
-        ? headers[AcceptClientHintsRequestHeaders.prefersColorScheme]?.toLowerCase()
-        : undefined
-      if (value === 'dark' || value === 'light' || value === 'no-preference') {
-        hints.prefersColorScheme = value
-        hints.firstRequest = false
-      }
-
-      // update the color scheme cookie
-      if (criticalClientHintsConfiguration.prefersColorSchemeOptions) {
-        if (!value || value === 'no-preference') {
-          hints.colorSchemeFromCookie = criticalClientHintsConfiguration.prefersColorSchemeOptions.defaultTheme
-        }
-        else {
-          hints.colorSchemeFromCookie = value === 'dark'
-            ? criticalClientHintsConfiguration.prefersColorSchemeOptions.darkThemeName
-            : criticalClientHintsConfiguration.prefersColorSchemeOptions.lightThemeName
-        }
-      }
-    }
-  }
-
-  if (hints.prefersReducedMotionAvailable && criticalClientHintsConfiguration.prefersReducedMotion) {
-    const value = headers[AcceptClientHintsRequestHeaders.prefersReducedMotion]?.toLowerCase()
-    if (value === 'no-preference' || value === 'reduce') {
-      hints.prefersReducedMotion = value
-      hints.firstRequest = false
-    }
-  }
-
-  if (hints.prefersReducedTransparencyAvailable && criticalClientHintsConfiguration.prefersReducedTransparency) {
-    const value = headers[AcceptClientHintsRequestHeaders.prefersReducedTransparency]?.toLowerCase()
-    if (value) {
-      hints.prefersReducedTransparency = value === 'reduce' ? 'reduce' : 'no-preference'
-      hints.firstRequest = false
-    }
-  }
-
-  if (hints.viewportHeightAvailable && criticalClientHintsConfiguration.viewportSize) {
-    const viewportHeight = lookupHeader(
-      'int',
-      AcceptClientHintsRequestHeaders.viewportHeight,
-      headers,
-    )
-    if (typeof viewportHeight === 'number') {
-      hints.firstRequest = false
-      hints.viewportHeight = viewportHeight
-    }
-    else {
-      hints.viewportHeight = criticalClientHintsConfiguration.clientHeight
-    }
-  }
-  else {
-    hints.viewportHeight = criticalClientHintsConfiguration.clientHeight
-  }
-
-  if (hints.viewportWidthAvailable && criticalClientHintsConfiguration.viewportSize) {
-    const viewportWidth = lookupHeader(
-      'int',
-      AcceptClientHintsRequestHeaders.viewportWidth,
-      headers,
-    )
-    if (typeof viewportWidth === 'number') {
-      hints.firstRequest = false
-      hints.viewportWidth = viewportWidth
-    }
-    else {
-      hints.viewportWidth = criticalClientHintsConfiguration.clientWidth
-    }
-  }
-  else {
-    hints.viewportWidth = criticalClientHintsConfiguration.clientWidth
-  }
-
-  if (hints.devicePixelRatioAvailable && criticalClientHintsConfiguration.viewportSize) {
-    const devicePixelRatio = lookupHeader(
-      'float',
-      AcceptClientHintsRequestHeaders.devicePixelRatio,
-      headers,
-    )
-    if (typeof devicePixelRatio === 'number') {
-      hints.firstRequest = false
-      try {
-        hints.devicePixelRatio = devicePixelRatio
-        if (!Number.isNaN(devicePixelRatio) && devicePixelRatio > 0) {
-          if (typeof hints.viewportWidth === 'number')
-            hints.viewportWidth = Math.round(hints.viewportWidth / devicePixelRatio)
-          if (typeof hints.viewportHeight === 'number')
-            hints.viewportHeight = Math.round(hints.viewportHeight / devicePixelRatio)
-        }
-      }
-      catch {
-        // just ignore
-      }
-    }
-  }
-
-  if (hints.widthAvailable && criticalClientHintsConfiguration.width) {
-    const width = lookupHeader(
-      'int',
-      AcceptClientHintsRequestHeaders.width,
-      headers,
-    )
-    if (typeof width === 'number') {
-      hints.firstRequest = false
-      hints.width = width
-    }
-  }
-
-  return hints
-}
-
-function writeClientHintsResponseHeaders(
-  criticalInfo: CriticalInfo,
-  criticalClientHintsConfiguration: CriticalClientHintsConfiguration,
-) {
-  // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Critical-CH
-  // Each header listed in the Critical-CH header should also be present in the Accept-CH and Vary headers.
-  const headers: Record<string, string[]> = {}
-
-  if (criticalClientHintsConfiguration.prefersColorScheme && criticalInfo.prefersColorSchemeAvailable)
-    writeClientHintHeaders(ClientHeaders, AcceptClientHintsHeaders.prefersColorScheme, headers)
-
-  if (criticalClientHintsConfiguration.prefersReducedMotion && criticalInfo.prefersReducedMotionAvailable)
-    writeClientHintHeaders(ClientHeaders, AcceptClientHintsHeaders.prefersReducedMotion, headers)
-
-  if (criticalClientHintsConfiguration.prefersReducedTransparency && criticalInfo.prefersReducedTransparencyAvailable)
-    writeClientHintHeaders(ClientHeaders, AcceptClientHintsHeaders.prefersReducedTransparency, headers)
-
-  if (criticalClientHintsConfiguration.viewportSize && criticalInfo.viewportHeightAvailable && criticalInfo.viewportWidthAvailable) {
-    writeClientHintHeaders(ClientHeaders, AcceptClientHintsHeaders.viewportHeight, headers)
-    writeClientHintHeaders(ClientHeaders, AcceptClientHintsHeaders.viewportWidth, headers)
-    if (criticalInfo.devicePixelRatioAvailable)
-      writeClientHintHeaders(ClientHeaders, AcceptClientHintsHeaders.devicePixelRatio, headers)
-  }
-
-  if (criticalClientHintsConfiguration.width && criticalInfo.widthAvailable)
-    writeClientHintHeaders(ClientHeaders, AcceptClientHintsHeaders.width, headers)
-
-  writeHeaders(headers)
-}
-
-function writeThemeCookie(
-  criticalInfo: CriticalInfo,
-  criticalClientHintsConfiguration: CriticalClientHintsConfiguration,
-) {
-  if (!criticalClientHintsConfiguration.prefersColorScheme || !criticalClientHintsConfiguration.prefersColorSchemeOptions)
-    return
-
-  const cookieName = criticalClientHintsConfiguration.prefersColorSchemeOptions.cookieName
-  const themeName = criticalInfo.colorSchemeFromCookie ?? criticalClientHintsConfiguration.prefersColorSchemeOptions.defaultTheme
-  const path = criticalClientHintsConfiguration.prefersColorSchemeOptions.baseUrl
-
-  const date = new Date()
-  const expires = new Date(date.setDate(date.getDate() + 365))
-  if (!criticalInfo.firstRequest || !criticalClientHintsConfiguration.reloadOnFirstRequest) {
-    useCookie(cookieName, {
-      path,
-      expires,
-      sameSite: 'lax',
-    }).value = themeName
-  }
-
-  return `${cookieName}=${themeName}; Path=${path}; Expires=${expires.toUTCString()}; SameSite=Lax`
-}