feat(modern): auto detect modern mode (#4422)

packages/config/src/config/_common.js

@@ -12,7 +12,7 @@ export default () => ({
 
   // Mode
   mode: 'universal',
-  modern: false,
+  modern: undefined,
 
   // Globals
   globalName: `nuxt`,

packages/config/src/options.js

@@ -253,10 +253,6 @@ export function getNuxtConfig(_options) {
   }
   defaultsDeep(options, modePreset || options.modes.universal)
 
-  if (options.modern === true) {
-    options.modern = 'server'
-  }
-
   // If no server-side rendering, add appear true transition
   /* istanbul ignore if */
   if (options.render.ssr === false && options.transition) {

packages/server/src/middleware/modern.js

@@ -1,3 +1,5 @@
+import chalk from 'chalk'
+import consola from 'consola'
 import { ModernBrowsers } from '@nuxt/common'
 import { matchesUA } from 'browserslist-useragent'
 
@@ -11,12 +13,33 @@ const isModernBrowser = (ua) => {
   })
 }
 
-export default function (req, res, next) {
+let detected = false
+
+const detectModernBuild = ({ options, resources }) => {
+  if (detected === false && ![false, 'client', 'server'].includes(options.modern)) {
+    detected = true
+    if (resources.modernManifest) {
+      options.modern = options.render.ssr ? 'server' : 'client'
+      consola.info(`Modern bundles are detected. Modern mode (${chalk.green.bold(options.modern)}) is enabled now.`)
+    } else {
+      options.modern = false
+    }
+  }
+}
+
+const detectModernBrowser = (req, options) => {
+  if (options.modern === 'server') {
     const { socket = {}, headers } = req
     if (socket.modernMode === undefined) {
       const ua = headers && headers['user-agent']
       socket.modernMode = isModernBrowser(ua)
     }
     req.modernMode = socket.modernMode
+  }
+}
+
+export default ({ context }) => (req, res, next) => {
+  detectModernBuild(context)
+  detectModernBrowser(req, context.options)
   next()
 }

packages/server/src/server.js

@@ -10,7 +10,7 @@ import renderAndGetWindow from './jsdom'
 import nuxtMiddleware from './middleware/nuxt'
 import errorMiddleware from './middleware/error'
 import Listener from './listener'
-import modernMiddleware from './middleware/modern'
+import createModernMiddleware from './middleware/modern'
 
 export default class Server {
   constructor(nuxt) {
@@ -79,12 +79,13 @@ export default class Server {
       }
     }
 
-    if (this.options.modern === 'server') {
+    const modernMiddleware = createModernMiddleware({
-      this.useMiddleware(modernMiddleware)
+      context: this.renderer.context
-    }
+    })
 
     // Add webpack middleware support only for development
     if (this.options.dev) {
+      this.useMiddleware(modernMiddleware)
       this.useMiddleware(async (req, res, next) => {
         const name = req.modernMode ? 'modern' : 'client'
         if (this.devMiddleware[name]) {
@@ -124,6 +125,7 @@ export default class Server {
           this.options.render.dist
         )
       })
+      this.useMiddleware(modernMiddleware)
     }
 
     // Add user provided middleware

packages/vue-renderer/src/renderer.js

@@ -223,7 +223,8 @@ export default class VueRenderer {
       rendererOptions
     )
 
-    if (this.context.options.modern === 'server') {
+    if (this.context.resources.modernManifest &&
+      !['client', false].includes(this.context.options.modern)) {
       this.renderer.modern = createBundleRenderer(
         this.context.resources.serverBundle,
         {

test/unit/modern.client.test.js

@@ -3,7 +3,7 @@ import { loadFixture, getPort, Nuxt, rp, wChunk } from '../utils'
 let nuxt, port
 const url = route => 'http://localhost:' + port + route
 
-describe('modern client mode', () => {
+describe('modern client mode (SSR)', () => {
   beforeAll(async () => {
     const options = await loadFixture('modern', { modern: 'client' })
     nuxt = new Nuxt(options)

test/unit/modern.server.test.js

@@ -1,17 +1,25 @@
+import chalk from 'chalk'
+import consola from 'consola'
 import { loadFixture, getPort, Nuxt, rp, wChunk } from '../utils'
 
 let nuxt, port
 const url = route => 'http://localhost:' + port + route
 const modernUA = 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.77 Safari/537.36'
+const modernInfo = mode => `Modern bundles are detected. Modern mode (${chalk.green.bold(mode)}) is enabled now.`
 
 describe('modern server mode', () => {
   beforeAll(async () => {
-    const options = await loadFixture('modern', { modern: 'server' })
+    const options = await loadFixture('modern')
     nuxt = new Nuxt(options)
     port = await getPort()
     await nuxt.server.listen(port, 'localhost')
   })
 
+  test('should detect server modern mode', async () => {
+    await nuxt.server.renderAndGetWindow(url('/'))
+    expect(consola.info).toHaveBeenCalledWith(modernInfo('server'))
+  })
+
   test('should use legacy resources by default', async () => {
     const response = await rp(url('/'))
     expect(response).toContain('/_nuxt/app.js')

test/unit/modern.spa.test.js

@@ -0,0 +1,53 @@
+import chalk from 'chalk'
+import consola from 'consola'
+import { loadFixture, getPort, Nuxt, rp } from '../utils'
+
+let nuxt, port, options
+const url = route => 'http://localhost:' + port + route
+const modernInfo = mode => `Modern bundles are detected. Modern mode (${chalk.green.bold(mode)}) is enabled now.`
+
+describe('modern client mode (SPA)', () => {
+  beforeAll(async () => {
+    options = await loadFixture('modern', { render: { ssr: false } })
+    nuxt = new Nuxt(options)
+    port = await getPort()
+    await nuxt.server.listen(port, 'localhost')
+  })
+
+  test('should detect client modern mode', async () => {
+    await nuxt.server.renderAndGetWindow(url('/'))
+    expect(consola.info).toHaveBeenCalledWith(modernInfo('client'))
+  })
+
+  test('should contain nomodule legacy resources', async () => {
+    const response = await rp(url('/'))
+    expect(response).toContain('src="/_nuxt/app.js" nomodule')
+    expect(response).toContain('src="/_nuxt/commons.app.js" nomodule')
+  })
+
+  test('should contain module modern resources', async () => {
+    const response = await rp(url('/'))
+    expect(response).toContain('<script type="module" src="/_nuxt/modern-app.js"')
+    expect(response).toContain('<script type="module" src="/_nuxt/modern-commons.app.js"')
+  })
+
+  test.skip('should contain module preload resources', async () => {
+    const response = await rp(url('/'))
+    expect(response).toContain('<link rel="modulepreload" href="/_nuxt/modern-app.js" as="script">')
+    expect(response).toContain('<link rel="modulepreload" href="/_nuxt/modern-commons.app.js" as="script">')
+  })
+
+  test('should contain module http2 pushed resources', async () => {
+    const { headers: { link } } = await rp(url('/'), { resolveWithFullResponse: true })
+    expect(link).toEqual([
+      '</_nuxt/modern-runtime.js>; rel=preload; as=script',
+      '</_nuxt/modern-commons.app.js>; rel=preload; as=script',
+      '</_nuxt/modern-app.js>; rel=preload; as=script'
+    ].join(', '))
+  })
+
+  // Close server and ask nuxt to stop listening to file changes
+  afterAll(async () => {
+    await nuxt.close()
+  })
+})