feat: try to detect global mixins adding meta info

src/shared/mixin.js

@@ -1,5 +1,6 @@
 import { triggerUpdate } from '../client/update'
 import { isUndefined, isFunction } from '../utils/is-type'
+import { find } from '../utils/array'
 import { ensuredPush } from '../utils/ensure'
 import { rootConfigKey } from './constants'
 import { hasMetaInfo } from './meta-helpers'
@@ -18,12 +19,13 @@ export default function createMixin (Vue, options) {
       const rootKey = '$root'
       const $root = this[rootKey]
       const $options = this.$options
+      const devtoolsEnabled = Vue.config.devtools
 
       Object.defineProperty(this, '_hasMetaInfo', {
         configurable: true,
         get () {
           // Show deprecation warning once when devtools enabled
-          if (Vue.config.devtools && !$root[rootConfigKey].deprecationWarningShown) {
+          if (devtoolsEnabled && !$root[rootConfigKey].deprecationWarningShown) {
             warn('VueMeta DeprecationWarning: _hasMetaInfo has been deprecated and will be removed in a future version. Please use hasMetaInfo(vm) instead')
             $root[rootConfigKey].deprecationWarningShown = true
           }
@@ -41,6 +43,17 @@ export default function createMixin (Vue, options) {
       if (!$root[rootConfigKey]) {
         $root[rootConfigKey] = { appId }
         appId++
+
+        if (devtoolsEnabled && $root.$options[options.keyName]) {
+          // use nextTick so the children should be added to $root
+          this.$nextTick(() => {
+            // find the first child that lists fnOptions
+            const child = find($root.$children, c => c.$vnode && c.$vnode.fnOptions)
+            if (child && child.$vnode.fnOptions[options.keyName]) {
+              warn(`VueMeta has detected a possible global mixin which adds a ${options.keyName} property to all Vue components on the page. This could cause severe performance issues. If possible, use $meta().addApp to add meta information instead`)
+            }
+          })
+        }
       }
 
       // to speed up updates we keep track of branches which have a component with vue-meta info defined
@@ -83,14 +96,18 @@ export default function createMixin (Vue, options) {
         $root[rootConfigKey].initialized = this.$isServer
 
         if (!$root[rootConfigKey].initialized) {
-          ensuredPush($options, 'beforeMount', function () {
-            const $root = this[rootKey]
-            // if this Vue-app was server rendered, set the appId to 'ssr'
-            // only one SSR app per page is supported
-            if ($root.$el && $root.$el.nodeType === 1 && $root.$el.hasAttribute('data-server-rendered')) {
-              $root[rootConfigKey].appId = options.ssrAppId
-            }
-          })
+          if (!$root[rootConfigKey].initializedSsr) {
+            $root[rootConfigKey].initializedSsr = true
+
+            ensuredPush($options, 'beforeMount', function () {
+              const $root = this
+              // if this Vue-app was server rendered, set the appId to 'ssr'
+              // only one SSR app per page is supported
+              if ($root.$el && $root.$el.nodeType === 1 && $root.$el.hasAttribute('data-server-rendered')) {
+                $root[rootConfigKey].appId = options.ssrAppId
+              }
+            })
+          }
 
           // we use the mounted hook here as on page load
           ensuredPush($options, 'mounted', function () {
@@ -154,6 +171,7 @@ export default function createMixin (Vue, options) {
       if (!this.$parent || !hasMetaInfo(this)) {
         return
       }
+      delete this._hasMetaInfo
 
       this.$nextTick(() => {
         if (!options.waitOnDestroyed || !this.$el || !this.$el.offsetParent) {

src/utils/array.js

@@ -11,6 +11,19 @@
 // which means the polyfills are removed for other build formats
 const polyfill = process.env.NODE_ENV === 'test'
 
+export function find (array, predicate, thisArg) {
+  if (polyfill && !Array.prototype.find) {
+    // idx needs to be a Number, for..in returns string
+    for (let idx = 0; idx < array.length; idx++) {
+      if (predicate.call(thisArg, array[idx], idx, array)) {
+        return array[idx]
+      }
+    }
+    return
+  }
+  return array.find(predicate, thisArg)
+}
+
 export function findIndex (array, predicate, thisArg) {
   if (polyfill && !Array.prototype.findIndex) {
     // idx needs to be a Number, for..in returns string

test/unit/utils.test.js

@@ -1,7 +1,7 @@
 /**
  * @jest-environment node
  */
-import { findIndex, includes, toArray } from '../../src/utils/array'
+import { find, findIndex, includes, toArray } from '../../src/utils/array'
 import { ensureIsArray } from '../../src/utils/ensure'
 import { hasGlobalWindowFn } from '../../src/utils/window'
 
@@ -29,6 +29,17 @@ describe('shared', () => {
   })
 
   /* eslint-disable no-extend-native */
+  test('find polyfill', () => {
+    const _find = Array.prototype.find
+    Array.prototype.find = false
+
+    const arr = [1, 2, 3]
+    expect(find(arr, (v, i) => i === 0)).toBe(1)
+    expect(find(arr, (v, i) => i === 3)).toBe(undefined)
+
+    Array.prototype.find = _find
+  })
+
   test('findIndex polyfill', () => {
     const _findIndex = Array.prototype.findIndex
     Array.prototype.findIndex = false