看源码的时候看到这个属性：

新手自然不知道这个是什么东西了，查了下vue  API：

https://router.vuejs.org/en/advanced/scroll-behavior.html

上面这个的意思就是当转到一个新的页面时，定位到最顶端。

Scroll Behavior

When using client-side routing, we may want to scroll to top when navigating to a new route, or preserve the scrolling position of history entries just like real page reload does. vue-router allows you to achieve these and even better, allows you to completely customize the scroll behavior on route navigation.

Note: this feature only works in HTML5 history mode.

When creating the router instance, you can provide the scrollBehavior function:

const router = new VueRouter({
  routes: [...],
  scrollBehavior (to, from, savedPosition) {
    // return desired position
  }
})

The scrollBehavior function receives the to and from route objects. The third argument, savedPosition, is only available if this is a popstatenavigation (triggered by the browser's back/forward buttons).

The function can return a scroll position object. The object could be in the form of:

• { x: number, y: number }
• { selector: string }

If a falsy value or an empty object is returned, no scrolling will happen.

For example:

scrollBehavior (to, from, savedPosition) {
  return { x: 0, y: 0 }
}

This will simply make the page scroll to top for all route navigations.

Returning the savedPosition will result in a native-like behavior when navigating with back/forward buttons:

scrollBehavior (to, from, savedPosition) {
  if (savedPosition) {
    return savedPosition
  } else {
    return { x: 0, y: 0 }
  }
}

If you want to simulate the "scroll to anchor" behavior:

scrollBehavior (to, from, savedPosition) {
  if (to.hash) {
    return {
      selector: to.hash
    }
  }
}

We can also use route meta fields to implement fine-grained scroll behavior control. Check out a full example here.