Solve v-for usage red reporting example in vue

This article mainly shares with you how to solve the red and warning problems when using v-for in vue. I hope it can help everyone. Code red reporting is very uncomfortable for patients with obsessive-compulsive disorder who pursue beautiful code. The red reporting is as follows:

There will also be in the console:

(Emitted value instead of an instance of Error) : component lists rendered with v-for should have explicit keys. See https://vuejs.org/guide/list. html#key for more info.

To solve this red reporting problem, we need to follow his prompts and add a unique key during the loop. Here we choose to use index:

<ul class="clearfix course-list">
<li class="left" v-for="(item,index)in gradeClassfy.primary.grade":key="index"><ahref="#">{{item.name}}</a></li>
</ul>

In this way, the red report disappears.

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