fix(scroll): run scrollBehavior on initial load (fix #3196) (#3199)

* Add handleScroll on initial history.transitionTo

* Update index.js

* test(scroll-behavior): add tests for scrollBehavior on load

* refactor(scroll-behavior): scrollBehavior on load

* style: remove spaces

* fix: handleScroll not called with from

* test(scroll-behavior): remove redundant tests

* fix: call handleScroll only if initial navigation succeeds

Co-authored-by: Eduardo San Martin Morote <posva13@gmail.com>

src/index.js

@@ -8,6 +8,7 @@ import { cleanPath } from './util/path'
 import { createMatcher } from './create-matcher'
 import { normalizeLocation } from './util/location'
 import { supportsPushState } from './util/push-state'
+import { handleScroll } from './util/scroll'
 
 import { HashHistory } from './history/hash'
 import { HTML5History } from './history/html5'
@@ -117,8 +118,18 @@ export default class VueRouter {
     const history = this.history
 
     if (history instanceof HTML5History || history instanceof HashHistory) {
-      const setupListeners = () => {
+      const handleInitialScroll = (routeOrError) => {
+        const from = history.current
+        const expectScroll = this.options.scrollBehavior
+        const supportsScroll = supportsPushState && expectScroll
+
+        if (supportsScroll && 'fullPath' in routeOrError) {
+          handleScroll(this, routeOrError, from, false)
+        }
+      }
+      const setupListeners = (routeOrError) => {
         history.setupListeners()
+        handleInitialScroll(routeOrError)
       }
       history.transitionTo(history.getCurrentLocation(), setupListeners, setupListeners)
     }

test/e2e/specs/scroll-behavior.js

@@ -119,6 +119,20 @@ module.exports = {
         null,
         'scroll to anchor that starts with number'
       )
+
+      .url('http://localhost:8080/scroll-behavior/bar#anchor')
+      .execute(function () {
+        location.reload(true)
+      })
+      .waitForElementVisible('#app', 1000)
+      .assert.evaluate(
+        function () {
+          return document.getElementById('anchor').getBoundingClientRect().top < 1
+        },
+        null,
+        'scroll to anchor on load'
+      )
+
       .end()
   }
 }