support BackTop to 2.0

examples/app.vue

@@ -44,6 +44,7 @@ li + li { border-left: solid 1px #bbb; padding-left: 10px; margin-left: 10px; }
                 <li><router-link to="/spin">Spin</router-link></li>
                 <li><router-link to="/cascader">Cascader</router-link></li>
                 <li><router-link to="/select">Select</router-link></li>
+                <li><router-link to="/backtop">Backtop</router-link></li>
             </ul>
         </nav>
         <router-view></router-view>

examples/main.js

@@ -140,6 +140,10 @@ const router = new VueRouter({
         {
             path: '/select',
             component: require('./routers/select.vue')
+        },
+        {
+            path: '/backtop',
+            component: require('./routers/back-top.vue')
         }
     ]
 });

examples/routers/back-top.vue

@@ -0,0 +1,15 @@
+<style>
+    body{
+        height: 2000px;
+    }
+</style>
+<template>
+    <BackTop>
+       
+    </BackTop>
+</template>
+<script>
+    export default {
+
+    }
+</script>