2.2.2 初始渲染的过渡

可以通过appear特性设置节点在初始渲染的过渡：

<transition appear>
  <!-- ... -->
</transition>

这里默认和进入/离开过渡一样，同样也可以自定义 CSS 类名。

<transition
  appear
  appear-class="custom-appear-class"
  appear-to-class="custom-appear-to-class" (2.1.8+)
  appear-active-class="custom-appear-active-class"
>
  <!-- ... -->
</transition>

自定义 JavaScript 钩子：

<transition
  appear
  v-on:before-appear="customBeforeAppearHook"
  v-on:appear="customAppearHook"
  v-on:after-appear="customAfterAppearHook"
  v-on:appear-cancelled="customAppearCancelledHook"
>
  <!-- ... -->
</transition>