Vue Performance

v-for with Ionic Components

When using v-for with Ionic components, we recommend using Vue's key attribute. This allows Vue to re-render loop elements in an efficient way by only updating the content inside of the component rather than re-creating the component altogether.

By using key you can provide a stable identity for each loop element so Vue can track insertions and deletions within the iterator. Below is an example of how to use key:

<template>  <ion-page>    <ion-content>      <ion-item v-for="item of items" :key="item.id">        <ion-label>{{ item.value }}</ion-label>      </ion-item>    </ion-content>  </ion-page></template>
<script>import { IonContent, IonItem, IonLabel, IonPage } from '@ionic/vue';import { defineComponent } from 'vue';
export default defineComponent({  components: {    IonContent,    IonItem,    IonLabel,    IonPage  },  setup() {    const items = ref([      { id: 0, value: 'Item 0' },      { id: 1, value: 'Item 1' },      ...    ]);        return { items }  }});</script>

In this example, we have an array of objects called items. Each object contains a value and an id. Using the key attribute, we pass the item.id for each object. This id is used to provide a stable identity for each loop element.

For more information on how Vue manages state with v-for see https://v3.vuejs.org/guide/list.html#maintaining-state