javascript - vue.js 我在 'v-once' 语句中使用了 'v-for' ，为什么找不到 'item' ？

Question

<div v-for="item in imControls.messages" >
    <p v-once>
        <span class="" v-if="item.type==3">{{item.name}}:</span>
        <span class="red" v-if="item.type==4">{{item.name}}:</span>
        <span class="blue" v-if="item.type==2">{{item.name}}:</span>
        <span class="grey" v-if="item.type==1">{{item.name}}:</span>
        <span v-html="item.text"></span>
    </p>
 </div>

imControls.messages 存在，如果我不在 p 标签上使用 v-once ，没关系，但如果我使用 v-once，找不到项目。

错误是

'vue.js:2574 [Vue warn]: Property or method "item" is not defined on the instance but referenced during render. Make sure to declare reactive data properties in the data option. (found in root instance)

vue.js:2217 Uncaught TypeError: Cannot read property 'type' of undefined'

Answer 1

v-once指令可以直接在v-for中使用

<div v-for="item in imControls.messages" v-once>
    <span class="" v-if="item.type==3">{{item.name}}:</span>
    <span class="red" v-if="item.type==4">{{item.name}}:</span>
    <span class="blue" v-if="item.type==2">{{item.name}}:</span>
    <span class="grey" v-if="item.type==1">{{item.name}}:</span>
    <span v-html="item.text"></span>
</div>