vuejs · posva · May 19, 2020 · Apr 13, 2020 · Apr 13, 2020 · May 12, 2020
diff --git a/examples/basic/app.js b/examples/basic/app.js
@@ -1,6 +1,30 @@
 import Vue from 'vue'
 import VueRouter from 'vue-router'
 
+// track number of popstate listeners
+let numPopstateListeners = 0
+const listenerCountDiv = document.createElement('div')
+listenerCountDiv.id = 'popstate-count'
+listenerCountDiv.textContent = numPopstateListeners + ' popstate listeners'
+document.body.appendChild(listenerCountDiv)
+
+const originalAddEventListener = window.addEventListener
+const originalRemoveEventListener = window.removeEventListener
+window.addEventListener = function (name, handler) {
+  if (name === 'popstate') {
+    listenerCountDiv.textContent =
+      ++numPopstateListeners + ' popstate listeners'
+  }
+  return originalAddEventListener.apply(this, arguments)
+}
+window.removeEventListener = function (name, handler) {
+  if (name === 'popstate') {
+    listenerCountDiv.textContent =
+      --numPopstateListeners + ' popstate listeners'
+  }
+  return originalRemoveEventListener.apply(this, arguments)
+}
+
 // 1. Use plugin.
 // This installs <router-view> and <router-link>,
 // and injects $router and $route to all router-enabled child components
@@ -27,7 +51,7 @@ const router = new VueRouter({
 // 4. Create and mount root instance.
 // Make sure to inject the router.
 // Route components will be rendered inside <router-view>.
-new Vue({
+const vueInstance = new Vue({
   router,
   data: () => ({ n: 0 }),
   template: `
@@ -69,3 +93,8 @@ new Vue({
     }
   }
 }).$mount('#app')
+
+document.getElementById('unmount').addEventListener('click', () => {
+  vueInstance.$destroy()
+  vueInstance.$el.innerHTML = ''
+})
diff --git a/examples/basic/index.html b/examples/basic/index.html
@@ -1,6 +1,8 @@
 <!DOCTYPE html>
 <link rel="stylesheet" href="/global.css">
 <a href="/">&larr; Examples index</a>
+<button id="unmount">Unmount</button>
+<hr />
 <div id="app"></div>
 <script src="/__build__/shared.chunk.js"></script>
 <script src="/__build__/basic.js"></script>
diff --git a/examples/hash-mode/app.js b/examples/hash-mode/app.js
@@ -1,6 +1,30 @@
 import Vue from 'vue'
 import VueRouter from 'vue-router'
 
+// track number of popstate listeners
+let numPopstateListeners = 0
+const listenerCountDiv = document.createElement('div')
+listenerCountDiv.id = 'popstate-count'
+listenerCountDiv.textContent = numPopstateListeners + ' popstate listeners'
+document.body.appendChild(listenerCountDiv)
+
+const originalAddEventListener = window.addEventListener
+const originalRemoveEventListener = window.removeEventListener
+window.addEventListener = function (name, handler) {
+  if (name === 'popstate') {
+    listenerCountDiv.textContent =
+      ++numPopstateListeners + ' popstate listeners'
+  }
+  return originalAddEventListener.apply(this, arguments)
+}
+window.removeEventListener = function (name, handler) {
+  if (name === 'popstate') {
+    listenerCountDiv.textContent =
+      --numPopstateListeners + ' popstate listeners'
+  }
+  return originalRemoveEventListener.apply(this, arguments)
+}
+
 // 1. Use plugin.
 // This installs <router-view> and <router-link>,
 // and injects $router and $route to all router-enabled child components
@@ -28,7 +52,7 @@ const router = new VueRouter({
 // 4. Create and mount root instance.
 // Make sure to inject the router.
 // Route components will be rendered inside <router-view>.
-new Vue({
+const vueInstance = new Vue({
   router,
   template: `
     <div id="app">
@@ -47,5 +71,12 @@ new Vue({
       <pre id="hash">{{ $route.hash }}</pre>
       <router-view class="view"></router-view>
     </div>
-  `
+  `,
+  methods: {
+  }
 }).$mount('#app')
+
+document.getElementById('unmount').addEventListener('click', () => {
+  vueInstance.$destroy()
+  vueInstance.$el.innerHTML = ''
+})
diff --git a/examples/hash-mode/index.html b/examples/hash-mode/index.html
@@ -1,6 +1,8 @@
 <!DOCTYPE html>
 <link rel="stylesheet" href="/global.css">
 <a href="/">&larr; Examples index</a>
+<button id="unmount">Unmount</button>
+<hr />
 <div id="app"></div>
 <script src="/__build__/shared.chunk.js"></script>
 <script src="/__build__/hash-mode.js"></script>
diff --git a/examples/index.html b/examples/index.html
@@ -27,6 +27,7 @@ <h1>Vue Router Examples</h1>
     <li><a href="discrete-components">Discrete Components</a></li>
     <li><a href="nested-router">Nested Routers</a></li>
     <li><a href="keepalive-view">Keepalive View</a></li>
+    <li><a href="multi-app">Multiple Apps</a></li>
   </ul>
 </body>
 </html>
diff --git a/examples/multi-app/app.js b/examples/multi-app/app.js
@@ -0,0 +1,75 @@
+import Vue from 'vue'
+import VueRouter from 'vue-router'
+
+// track number of popstate listeners
+let numPopstateListeners = 0
+const listenerCountDiv = document.getElementById('popcount')
+listenerCountDiv.textContent = 0
+
+const originalAddEventListener = window.addEventListener
+const originalRemoveEventListener = window.removeEventListener
+window.addEventListener = function (name, handler) {
+  if (name === 'popstate') {
+    listenerCountDiv.textContent =
+      ++numPopstateListeners
+  }
+  return originalAddEventListener.apply(this, arguments)
+}
+window.removeEventListener = function (name, handler) {
+  if (name === 'popstate') {
+    listenerCountDiv.textContent =
+      --numPopstateListeners
+  }
+  return originalRemoveEventListener.apply(this, arguments)
+}
+
+// 1. Use plugin.
+// This installs <router-view> and <router-link>,
+// and injects $router and $route to all router-enabled child components
+Vue.use(VueRouter)
+
+const looper = [1, 2, 3]
+
+looper.forEach((n) => {
+  let vueInstance
+  const mountEl = document.getElementById('mount' + n)
+  const unmountEl = document.getElementById('unmount' + n)
+
+  mountEl.addEventListener('click', () => {
+    // 2. Define route components
+    const Home = { template: '<div>home</div>' }
+    const Foo = { template: '<div>foo</div>' }
+
+    // 3. Create the router
+    const router = new VueRouter({
+      mode: 'history',
+      base: __dirname,
+      routes: [
+        { path: '/', component: Home },
+        { path: '/foo', component: Foo }
+      ]
+    })
+
+    // 4. Create and mount root instance.
+    // Make sure to inject the router.
+    // Route components will be rendered inside <router-view>.
+    vueInstance = new Vue({
+      router,
+      template: `
+        <div id="app-${n}">
+          <h1>Basic</h1>
+          <ul>
+            <li><router-link to="/">/</router-link></li>
+            <li><router-link to="/foo">/foo</router-link></li>
+          </ul>
+          <router-view class="view"></router-view>
+        </div>
+      `
+    }).$mount('#app-' + n)
+  })
+
+  unmountEl.addEventListener('click', () => {
+    vueInstance.$destroy()
+    vueInstance.$el.innerHTML = ''
+  })
+})
diff --git a/examples/multi-app/index.html b/examples/multi-app/index.html
@@ -0,0 +1,24 @@
+<!DOCTYPE html>
+<link rel="stylesheet" href="/global.css">
+<a href="/">&larr; Examples index</a>
+
+<button id="mount1">Mount App 1</button>
+<button id="mount2">Mount App 2</button>
+<button id="mount3">Mount App 3</button>
+
+<hr />
+
+<button id="unmount1">Unmount App 1</button>
+<button id="unmount2">Unmount App 2</button>
+<button id="unmount3">Unmount App 3</button>
+
+<hr />
+
+popstate count: <span id="popcount"></span>
+
+<div id="app-1"></div>
+<div id="app-2"></div>
+<div id="app-3"></div>
+
+<script src="/__build__/shared.chunk.js"></script>
+<script src="/__build__/multi-app.js"></script>
diff --git a/src/history/base.js b/src/history/base.js
@@ -23,13 +23,16 @@ export class History {
   readyCbs: Array<Function>
   readyErrorCbs: Array<Function>
   errorCbs: Array<Function>
+  listeners: Array<Function>
+  cleanupListeners: Function
 
   // implemented by sub-classes
   +go: (n: number) => void
   +push: (loc: RawLocation) => void
   +replace: (loc: RawLocation) => void
   +ensureURL: (push?: boolean) => void
   +getCurrentLocation: () => string
+  +setupListeners: Function
 
   constructor (router: Router, base: ?string) {
     this.router = router
@@ -41,6 +44,7 @@ export class History {
     this.readyCbs = []
     this.readyErrorCbs = []
     this.errorCbs = []
+    this.listeners = []
   }
 
   listen (cb: Function) {
@@ -208,6 +212,17 @@ export class History {
       hook && hook(route, prev)
     })
   }
+
+  setupListeners () {
+    // Default implementation is empty
+  }
+
+  teardownListeners () {
+    this.listeners.forEach(cleanupListener => {
+      cleanupListener()
+    })
+    this.listeners = []
+  }
 }
 
 function normalizeBase (base: ?string): string {

diff --git a/src/history/hash.js b/src/history/hash.js
@@ -20,31 +20,40 @@ export class HashHistory extends History {
   // this is delayed until the app mounts
   // to avoid the hashchange listener being fired too early
   setupListeners () {
+    if (this.listeners.length > 0) {
+      return
+    }
+
     const router = this.router
     const expectScroll = router.options.scrollBehavior
     const supportsScroll = supportsPushState && expectScroll
 
     if (supportsScroll) {
-      setupScroll()
+      this.listeners.push(setupScroll())
     }
 
-    window.addEventListener(
-      supportsPushState ? 'popstate' : 'hashchange',
-      () => {
-        const current = this.current
-        if (!ensureSlash()) {
-          return
-        }
-        this.transitionTo(getHash(), route => {
-          if (supportsScroll) {
-            handleScroll(this.router, route, current, true)
-          }
-          if (!supportsPushState) {
-            replaceHash(route.fullPath)
-          }
-        })
+    const handleRoutingEvent = () => {
+      const current = this.current
+      if (!ensureSlash()) {
+        return
       }
+      this.transitionTo(getHash(), route => {
+        if (supportsScroll) {
+          handleScroll(this.router, route, current, true)
+        }
+        if (!supportsPushState) {
+          replaceHash(route.fullPath)
+        }
+      })
+    }
+    const eventType = supportsPushState ? 'popstate' : 'hashchange'
+    window.addEventListener(
+      eventType,
+      handleRoutingEvent
     )
+    this.listeners.push(() => {
+      window.removeEventListener(eventType, handleRoutingEvent)
+    })
   }
 
   push (location: RawLocation, onComplete?: Function, onAbort?: Function) {

diff --git a/src/history/html5.js b/src/history/html5.js
@@ -8,24 +8,34 @@ import { setupScroll, handleScroll } from '../util/scroll'
 import { pushState, replaceState, supportsPushState } from '../util/push-state'
 
 export class HTML5History extends History {
+  _startLocation: string
+
   constructor (router: Router, base: ?string) {
     super(router, base)
 
+    this._startLocation = getLocation(this.base)
+  }
+
+  setupListeners () {
+    if (this.listeners.length > 0) {
+      return
+    }
+
+    const router = this.router
     const expectScroll = router.options.scrollBehavior
     const supportsScroll = supportsPushState && expectScroll
 
     if (supportsScroll) {
-      setupScroll()
+      this.listeners.push(setupScroll())
     }
 
-    const initLocation = getLocation(this.base)
-    window.addEventListener('popstate', e => {
+    const handleRoutingEvent = () => {
       const current = this.current
 
       // Avoiding first `popstate` event dispatched in some browsers but first
       // history route not updated since async guard at the same time.
       const location = getLocation(this.base)
-      if (this.current === START && location === initLocation) {
+      if (this.current === START && location === this._startLocation) {
         return
       }
 
@@ -34,6 +44,10 @@ export class HTML5History extends History {
           handleScroll(router, route, current, true)
         }
       })
+    }
+    window.addEventListener('popstate', handleRoutingEvent)
+    this.listeners.push(() => {
+      window.removeEventListener('popstate', handleRoutingEvent)
     })
   }