feat: scrollBehavior accept returning a promise (#1758)

homerjam · yyx990803 · commit ce13b55f063b · 2017-10-11T15:54:21.000-04:00
diff --git a/examples/scroll-behavior/app.js b/examples/scroll-behavior/app.js
@@ -3,11 +3,11 @@ import VueRouter from 'vue-router'
 
 Vue.use(VueRouter)
 
-const Home = { template: '<div>home</div>' }
-const Foo = { template: '<div>foo</div>' }
+const Home = { template: '<div class="home">home</div>' }
+const Foo = { template: '<div class="foo">foo</div>' }
 const Bar = {
   template: `
-    <div>
+    <div class="bar">
       bar
       <div style="height:500px"></div>
       <p id="anchor" style="height:500px">Anchor</p>
@@ -20,32 +20,42 @@ const Bar = {
 // - only available in html5 history mode
 // - defaults to no scroll behavior
 // - return false to prevent scroll
-const scrollBehavior = (to, from, savedPosition) => {
+const scrollBehavior = function (to, from, savedPosition) {
   if (savedPosition) {
     // savedPosition is only available for popstate navigations.
     return savedPosition
   } else {
-    const position = {}
-    // new navigation.
-    // scroll to anchor by returning the selector
-    if (to.hash) {
-      position.selector = to.hash
+    return new Promise(resolve => {
+      const position = {}
+      let delay = 500
+      // new navigation.
+      // scroll to anchor by returning the selector
+      if (to.hash) {
+        position.selector = to.hash
 
-      // specify offset of the element
-      if (to.hash === '#anchor2') {
-        position.offset = { y: 100 }
+        // specify offset of the element
+        if (to.hash === '#anchor2') {
+          position.offset = { y: 100 }
+        }
+
+        if (document.querySelector(to.hash)) {
+          delay = 0
+        }
+      }
+      // check if any matched route config has meta that requires scrolling to top
+      if (to.matched.some(m => m.meta.scrollToTop)) {
+        // coords will be used if no selector is provided,
+        // or if the selector didn't match any element.
+        position.x = 0
+        position.y = 0
       }
-    }
-    // check if any matched route config has meta that requires scrolling to top
-    if (to.matched.some(m => m.meta.scrollToTop)) {
-      // cords will be used if no selector is provided,
-      // or if the selector didn't match any element.
-      position.x = 0
-      position.y = 0
-    }
-    // if the returned position is falsy or an empty object,
-    // will retain current scroll position.
-    return position
+      // wait for the out transition to complete (if necessary)
+      setTimeout(() => {
+        // if the returned position is falsy or an empty object,
+        // will retain current scroll position.
+        resolve(position)
+      }, delay)
+    })
   }
 }
 
@@ -72,7 +82,9 @@ new Vue({
         <li><router-link to="/bar#anchor">/bar#anchor</router-link></li>
         <li><router-link to="/bar#anchor2">/bar#anchor2</router-link></li>
       </ul>
-      <router-view class="view"></router-view>
+      <transition name="fade" mode="out-in">
+        <router-view class="view"></router-view>
+      </transition>
     </div>
   `
 }).$mount('#app')
diff --git a/examples/scroll-behavior/index.html b/examples/scroll-behavior/index.html
@@ -1,6 +1,12 @@
 <!DOCTYPE html>
 <link rel="stylesheet" href="/global.css">
 <style>
+.fade-enter-active, .fade-leave-active {
+  transition: opacity .5s ease;
+}
+.fade-enter, .fade-leave-active {
+  opacity: 0
+}
 .view {
   border: 1px solid red;
   height: 2000px;
diff --git a/src/util/scroll.js b/src/util/scroll.js
@@ -38,27 +38,19 @@ export function handleScroll (
 
   // wait until re-render finishes before scrolling
   router.app.$nextTick(() => {
-    let position = getScrollPosition()
+    const position = getScrollPosition()
     const shouldScroll = behavior(to, from, isPop ? position : null)
+
     if (!shouldScroll) {
       return
     }
-    const isObject = typeof shouldScroll === 'object'
-    if (isObject && typeof shouldScroll.selector === 'string') {
-      const el = document.querySelector(shouldScroll.selector)
-      if (el) {
-        let offset = shouldScroll.offset && typeof shouldScroll.offset === 'object' ? shouldScroll.offset : {}
-        offset = normalizeOffset(offset)
-        position = getElementPosition(el, offset)
-      } else if (isValidPosition(shouldScroll)) {
-        position = normalizePosition(shouldScroll)
-      }
-    } else if (isObject && isValidPosition(shouldScroll)) {
-      position = normalizePosition(shouldScroll)
-    }
 
-    if (position) {
-      window.scrollTo(position.x, position.y)
+    if (typeof shouldScroll.then === 'function') {
+      shouldScroll.then(shouldScroll => {
+        scrollToPosition(shouldScroll, position)
+      })
+    } else {
+      scrollToPosition(shouldScroll, position)
     }
   })
 }
@@ -111,3 +103,23 @@ function normalizeOffset (obj: Object): Object {
 function isNumber (v: any): boolean {
   return typeof v === 'number'
 }
+
+function scrollToPosition (shouldScroll, position) {
+  const isObject = typeof shouldScroll === 'object'
+  if (isObject && typeof shouldScroll.selector === 'string') {
+    const el = document.querySelector(shouldScroll.selector)
+    if (el) {
+      let offset = shouldScroll.offset && typeof shouldScroll.offset === 'object' ? shouldScroll.offset : {}
+      offset = normalizeOffset(offset)
+      position = getElementPosition(el, offset)
+    } else if (isValidPosition(shouldScroll)) {
+      position = normalizePosition(shouldScroll)
+    }
+  } else if (isObject && isValidPosition(shouldScroll)) {
+    position = normalizePosition(shouldScroll)
+  }
+
+  if (position) {
+    window.scrollTo(position.x, position.y)
+  }
+}
diff --git a/test/e2e/nightwatch.config.js b/test/e2e/nightwatch.config.js
@@ -33,7 +33,12 @@ module.exports = {
       'desiredCapabilities': {
         'browserName': 'chrome',
         'javascriptEnabled': true,
-        'acceptSslCerts': true
+        'acceptSslCerts': true,
+        'chromeOptions': {
+          'args': [
+            'window-size=1280,800'
+          ]
+        }
       }
     },
 
diff --git a/test/e2e/specs/scroll-behavior.js b/test/e2e/specs/scroll-behavior.js
@@ -1,5 +1,7 @@
 module.exports = {
   'scroll behavior': function (browser) {
+    const TIMEOUT = 2000
+
     browser
     .url('http://localhost:8080/scroll-behavior/')
       .waitForElementVisible('#app', 1000)
@@ -10,11 +12,13 @@ module.exports = {
         window.scrollTo(0, 100)
       })
       .click('li:nth-child(2) a')
+      .waitForElementPresent('.view.foo', TIMEOUT)
       .assert.containsText('.view', 'foo')
       .execute(function () {
         window.scrollTo(0, 200)
         window.history.back()
       })
+      .waitForElementPresent('.view.home', TIMEOUT)
       .assert.containsText('.view', 'home')
       .assert.evaluate(function () {
         return window.pageYOffset === 100
@@ -45,6 +49,7 @@ module.exports = {
         window.scrollTo(0, 50)
         window.history.forward()
       })
+      .waitForElementPresent('.view.foo', TIMEOUT)
       .assert.containsText('.view', 'foo')
       .assert.evaluate(function () {
         return window.pageYOffset === 200
@@ -53,12 +58,14 @@ module.exports = {
       .execute(function () {
         window.history.back()
       })
+      .waitForElementPresent('.view.home', TIMEOUT)
       .assert.containsText('.view', 'home')
       .assert.evaluate(function () {
         return window.pageYOffset === 50
       }, null, 'restore scroll position on back again')
 
       .click('li:nth-child(3) a')
+      .waitForElementPresent('.view.bar', TIMEOUT)
       .assert.evaluate(function () {
         return window.pageYOffset === 0
       }, null, 'scroll to top on new entry')
@@ -68,7 +75,9 @@ module.exports = {
         return document.getElementById('anchor').getBoundingClientRect().top < 1
       }, null, 'scroll to anchor')
 
-      .click('li:nth-child(5) a')
+      .execute(function () {
+        document.querySelector('li:nth-child(5) a').click()
+      })
       .assert.evaluate(function () {
         return document.getElementById('anchor2').getBoundingClientRect().top < 101
       }, null, 'scroll to anchor with offset')
