https://github.com/vuejs/vetur/issues/858
<script src="https://vuejs.org/js/vue.min.js"></script>
<div id="demo">
<div class="row" v-for="i in Math.ceil(items.length / 5)">
<span v-for="item in items.slice((i - 1) * 5, i * 5)">
{{item}}
</span>
</div>
</div>这段代码会有提示错误，
但是在jsfiddle里面，可以正常运行 https://jsfiddle.net/ud25tGNwMddCP7JI/jc1u78r0/1/
Elements in iteration expect to have 'v-bind:key' directives
原文：https://www.cnblogs.com/chucklu/p/14207283.html