"Property or method is not defined on the instance but referenced during render"

Question

我需要在 <v-carousel> 之外显示 item.title 但我收到此错误消息：

[Vue warn]: Property or method "item" is not defined on the instance but referenced during render. Make sure that this property is reactive, either in the data option, or for class-based components, by initializing the property. See: https://vuejs.org/v2/guide/reactivity.html#Declaring-Reactive-Properties.

我检查了 Whosebug 搜索的结果，但我真的很难理解它。如果有人可以通过这个例子向我解释，我将不胜感激。这是我的代码：

<v-carousel>
<v-carousel-item v-for="(item,i) in items" v-bind:src="item.src" :key="i">
</v-carousel-item>
</v-carousel>

<h1>TITLE: {{ item.title }}</h1>

<script>
  export default {
    data () {
      return {
        items: [
          {
            src: '/static/a.jpg',
            title: 'A',
            text: 'texta'
          },
          {
            src: '/static/b.jpg',
            title: 'B',
            text: 'textb'
          }
          {
      }
    }
  }
</script>

这是我需要归档的内容：

一旦图像更改为下一个 - 范围的 outside 文本也应该更改。我试图检查范围外的项目数组的值，但它没有用： <h1 v-if="(item,i) === 1">Lion</h1> <h1 v-if="(item,i) === 2">Ape</h1> 如何在范围外访问当前轮播项的值？

Answer 1

您需要在 v-carousel 组件上添加 v-model：

<v-carousel v-model="carousel">
    <v-carousel-item 
        v-for="(item,i) in items"
        v-bind:src="item.src"          
        :key="i"
    ></v-carousel-item>
</v-carousel>
//then set title like this:
<h1>TITLE: {{ items[carousel].title }}</h1>

并将carousel变量添加到data

data () {
  return {
    carousel: 0, //like this
    items: [
       ...

"Property or method is not defined on the instance but referenced during render"

"Property or method is not defined on the instance but referenced during render"

vuejs2

vuetify.js

vue-reactivity