✨ add router scroll behaviour

Author: dcastil

packages/@vuepress/core/lib/app/app.js

@@ -23,7 +23,7 @@ if (module.hot) {
     if (siteData.base !== prevBase) {
       window.alert(
         `[vuepress] Site base has changed. ` +
-        `Please restart dev server to ensure correct asset paths.`
+          `Please restart dev server to ensure correct asset paths.`
       )
     }
   })
@@ -62,15 +62,25 @@ export function createApp (isServer) {
     base: siteData.base,
     mode: 'history',
     fallback: false,
-    routes
+    routes,
+    scrollBehavior (to, from, savedPosition) {
+      if (savedPosition) {
+        return savedPosition
+      }
+      if (to.path !== from.path) {
+        return { x: 0, y: 0 }
+      }
+    }
   })
 
   // redirect /foo to /foo/
   router.beforeEach((to, from, next) => {
     if (!/(\/|\.html)$/.test(to.path)) {
-      next(Object.assign({}, to, {
-        path: to.path + '/'
-      }))
+      next(
+        Object.assign({}, to, {
+          path: to.path + '/'
+        })
+      )
     } else {
       next()
     }
@@ -94,7 +104,11 @@ export function createApp (isServer) {
       render (h) {
         return h('div', { attrs: { id: 'app' }}, [
           h('router-view', { ref: 'layout' }),
-          h('div', { class: 'global-ui' }, globalUIComponents.map(component => h(component)))
+          h(
+            'div',
+            { class: 'global-ui' },
+            globalUIComponents.map(component => h(component))
+          )
         ])
       }
     })