How to use vfor in vue

The v-for directive in Vue.js is used to traverse an array or object to dynamically render a list of items by providing an item to represent the current item and an optional index to represent the current index. This directive can be used to iterate over arrays and objects and specify unique keys using the :key attribute to optimize performance.

Usage of v-for in Vue.js

v-for is used for traversal in Vue.js A built-in directive for arrays or objects. It allows you to dynamically render items in a list while providing each item with a unique key.

Syntax

<code><template v-for="(item, index) in collection">
  <!-- 渲染项目 -->
</template></code>

Parameters

<li> item: The current item in the list. <li> index: The index of the current project (optional). <li> collection: The array or object to be traversed.

Usage

Iterate through the array

<code><ul>
  <li v-for="item in names">{{ item }}</li>
</ul></code>

This will names in the array Creates a <li> element for each item and displays the item value.

Iterate over the objects

<code><ul>
  <li v-for="key in object">{{ key }}: {{ object[key] }}</li>
</ul></code>

This will create a <li> element for each key in the object object , and displays the key and value.

Using index

The v-for directive also has an optional index parameter, which provides the index of the current project:

<code><ul>
  <li v-for="(item, index) in names">{{ index + 1 }}: {{ item }}</li>
</ul></code>

Unique Key

Each v-for item must have a unique key. This is because Vue.js uses this key to track changes to the item and update the DOM efficiently. You can specify a key for a project using the :key attribute:

<code><ul>
  <li v-for="item in names" :key="item">{{ item }}</li>
</ul></code>

If you don't provide a key, Vue.js will use the current project as the default key. However, using explicit keys can improve performance.

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