feat(scroll): handle id selectors starting with a number

Closes #2163

Author: posva

Diff for: examples/scroll-behavior/app.js

@@ -37,7 +37,8 @@ const scrollBehavior = function (to, from, savedPosition) {
         position.offset = { y: 100 }
       }
 
-      if (document.querySelector(to.hash)) {
+      // bypass #1number check
+      if (/^#\d/.test(to.hash) || document.querySelector(to.hash)) {
         return position
       }
 
@@ -87,6 +88,7 @@ new Vue({
         <li><router-link to="/bar">/bar</router-link></li>
         <li><router-link to="/bar#anchor">/bar#anchor</router-link></li>
         <li><router-link to="/bar#anchor2">/bar#anchor2</router-link></li>
+        <li><router-link to="/bar#1number">/bar#1number</router-link></li>
       </ul>
       <transition name="fade" mode="out-in" @after-leave="afterLeave">
         <router-view class="view"></router-view>

Diff for: src/util/scroll.js

@@ -45,20 +45,27 @@ export function handleScroll (
   // wait until re-render finishes before scrolling
   router.app.$nextTick(() => {
     const position = getScrollPosition()
-    const shouldScroll = behavior.call(router, to, from, isPop ? position : null)
+    const shouldScroll = behavior.call(
+      router,
+      to,
+      from,
+      isPop ? position : null
+    )
 
     if (!shouldScroll) {
       return
     }
 
     if (typeof shouldScroll.then === 'function') {
-      shouldScroll.then(shouldScroll => {
-        scrollToPosition((shouldScroll: any), position)
-      }).catch(err => {
-        if (process.env.NODE_ENV !== 'production') {
-          assert(false, err.toString())
-        }
-      })
+      shouldScroll
+        .then(shouldScroll => {
+          scrollToPosition((shouldScroll: any), position)
+        })
+        .catch(err => {
+          if (process.env.NODE_ENV !== 'production') {
+            assert(false, err.toString())
+          }
+        })
     } else {
       scrollToPosition(shouldScroll, position)
     }
@@ -114,12 +121,22 @@ function isNumber (v: any): boolean {
   return typeof v === 'number'
 }
 
+const hashStartsWithNumberRE = /^#\d/
+
 function scrollToPosition (shouldScroll, position) {
   const isObject = typeof shouldScroll === 'object'
   if (isObject && typeof shouldScroll.selector === 'string') {
-    const el = document.querySelector(shouldScroll.selector)
+    // getElementById would still fail if the selector contains a more complicated query like #main[data-attr]
+    // but at the same time, it doesn't make much sense to select an element with an id and an extra selector
+    const el = hashStartsWithNumberRE.test(shouldScroll.selector) // $flow-disable-line
+      ? document.getElementById(shouldScroll.selector.slice(1)) // $flow-disable-line
+      : document.querySelector(shouldScroll.selector)
+
     if (el) {
-      let offset = shouldScroll.offset && typeof shouldScroll.offset === 'object' ? shouldScroll.offset : {}
+      let offset =
+        shouldScroll.offset && typeof shouldScroll.offset === 'object'
+          ? shouldScroll.offset
+          : {}
       offset = normalizeOffset(offset)
       position = getElementPosition(el, offset)
     } else if (isValidPosition(shouldScroll)) {

Diff for: test/e2e/specs/scroll-behavior.js

@@ -11,7 +11,7 @@ module.exports = {
     browser
       .url('http://localhost:8080/scroll-behavior/')
       .waitForElementVisible('#app', 1000)
-      .assert.count('li a', 5)
+      .assert.count('li a', 6)
       .assert.containsText('.view', 'home')
 
       .execute(function () {
@@ -117,6 +117,16 @@ module.exports = {
         null,
         'scroll to anchor with offset'
       )
+      .execute(function () {
+        document.querySelector('li:nth-child(6) a').click()
+      })
+      .assert.evaluate(
+        function () {
+          return document.getElementById('1number').getBoundingClientRect().top < 1
+        },
+        null,
+        'scroll to anchor that starts with number'
+      )
       .end()
   }
 }