vue-router中scrollBehavior的巧妙用法

<div id="app">
  <keep-alive>
   <router-view v-if="$route.meta.keepalive"></router-view>
  </keep-alive>
  <router-view v-if="!$route.meta.keepalive"></router-view>
</div>
const router = new router({
 scrollbehavior(to, from, savedposition) {
  if (savedposition && to.meta.keepalive) {
   return savedposition;
  }
  return { x: 0, y:0 };
 },
});

// fetchcourselist是一个封装好的promise请求
fetchcourselist().then(({ data: courses }) => {
 this.courses = courses;
}).then(() => {
  settimeout(() => {
    window.scrollto(0, 1);
    window.scrollto(0, 0);
  });
});

const router = new router({
 scrollbehavior(to, from, savedposition) {
  // keep-alive 返回缓存页面后记录浏览位置
  if (savedposition && to.meta.keepalive) {
   return savedposition;
  }
  // 异步滚动操作
  return new promise((resolve) => {
   settimeout(() => {
    resolve({ x: 0, y: 1 });
   }, 0);
  });
 },
});