fix: preserve history state when reloading

examples/basic/app.js

@@ -48,6 +48,7 @@ new Vue({
             <a :href="props.href" @click="props.navigate">{{ props.route.path }} (with v-slot).</a>
           </li>
         </router-link>
+        <li><router-link to="/foo" replace>/foo (replace)</router-link></li>
       </ul>
       <button id="navigate-btn" @click="navigateAndIncrement">On Success</button>
       <pre id="counter">{{ n }}</pre>

src/util/scroll.js

@@ -3,6 +3,7 @@
 import type Router from '../index'
 import { assert } from './warn'
 import { getStateKey, setStateKey } from './state-key'
+import { extend } from './misc'
 
 const positionStore = Object.create(null)
 
@@ -14,7 +15,10 @@ export function setupScroll () {
   // location.host contains the port and location.hostname doesn't
   const protocolAndPath = window.location.protocol + '//' + window.location.host
   const absolutePath = window.location.href.replace(protocolAndPath, '')
-  window.history.replaceState({ key: getStateKey() }, '', absolutePath)
+  // preserve existing history state as it could be overriden by the user
+  const stateCopy = extend({}, window.history.state)
+  stateCopy.key = getStateKey()
+  window.history.replaceState(stateCopy, '', absolutePath)
   window.addEventListener('popstate', e => {
     saveScrollPosition()
     if (e.state && e.state.key) {

test/e2e/specs/basic.js

@@ -9,8 +9,8 @@ module.exports = {
     browser
       .url('http://localhost:8080/basic/')
       .waitForElementVisible('#app', 1000)
-      .assert.count('li', 8)
-      .assert.count('li a', 8)
+      .assert.count('li', 9)
+      .assert.count('li a', 9)
       // assert correct href with base
       .assert.attributeContains('li:nth-child(1) a', 'href', '/basic/')
       .assert.attributeContains('li:nth-child(2) a', 'href', '/basic/foo')

test/e2e/specs/history-state.js

@@ -0,0 +1,56 @@
+const bsStatus = require('../browserstack-send-status')
+
+module.exports = {
+  ...bsStatus(),
+
+  '@tags': ['history'],
+
+  'history state': function (browser) {
+    browser
+      .url('http://localhost:8080/scroll-behavior/')
+      .waitForElementVisible('#app', 1000)
+
+      .execute(function () {
+        window.scrollTo(0, 100)
+        const key = window.history.state.key
+        window.history.replaceState({ key, foo: 'foo' }, '', window.location.pathname)
+      })
+      .url('http://localhost:8080/scroll-behavior/')
+      .waitForElementVisible('#app', 1000)
+      .assert.evaluate(function () {
+        return window.history.state.foo === 'foo'
+      }, null, 'keeps existing state when reloading')
+
+      // check on navigation
+      .url('http://localhost:8080/basic/')
+      .click('li:nth-child(2) a')
+      .assert.urlEquals('http://localhost:8080/basic/foo')
+      .execute(function () {
+        window.scrollTo(0, 100)
+        const key = window.history.state.key
+        window.history.replaceState({ key, foo: 'foo' }, '', window.location.pathname)
+      })
+      .click('li:nth-child(3) a')
+      .assert.urlEquals('http://localhost:8080/basic/bar')
+      .execute(function () {
+        window.history.back()
+      })
+      .assert.evaluate(function () {
+        return window.history.state.foo === 'foo'
+      }, null, 'keeps existing state when navigating back')
+      .click('li:nth-child(3) a')
+      .assert.urlEquals('http://localhost:8080/basic/bar')
+      .execute(function () {
+        window.scrollTo(0, 100)
+        const key = window.history.state.key
+        window.history.replaceState({ key, bar: 'bar' }, '', window.location.pathname)
+      })
+      .click('li:nth-child(9) a')
+      .assert.urlEquals('http://localhost:8080/basic/foo')
+      .assert.evaluate(function () {
+        return window.history.state.bar === 'bar'
+      }, null, 'keeps existing state when replacing')
+
+      .end()
+  }
+}