Transition Group Root Element

破壊的変更

#

Overview #

<transition-group> no longer renders a root element by default, but can still create one with the tag attribute.

2.x Syntax #

In Vue 2, <transition-group>, like other custom components, needed a root element, which by default was a <span> but was customizable via the tag attribute.

<transition-group tag="ul">
  <li v-for="item in items" :key="item">
    {{ item }}
  </li>
</transition-group>

3.x Syntax #

In Vue 3, we have fragment support, so components no longer need a root node. Consequently, <transition-group> no longer renders one by default.

• If you already have the tag attribute defined in your Vue 2 code, like in the example above, everything will work as before
• If you didn't have one defined and your styling or other behaviors relied on the presence of the <span> root element to work properly, simply add tag="span" to the <transition-group>:

<transition-group tag="span">
  <!-- -->
</transition-group>

Migration Strategy #

Migration build flag: TRANSITION_GROUP_ROOT

See also #

• Some transition classes got a rename
• <Transition> as a root can no longer be toggled from the outside