v-show如果使用循环对象的属性来时控制, 这个属性必须是加载时就存在的
<div class="list-group col-sm-12" v-for="(issue,index) in issue_list">
<a @click="switch_comments(issue, index)" style="background-color:#5cb85c;font-weight:bold;" href="#" class="list-group-item">
<span class="glyphicon glyphicon-star"></span> {{index+1}}. {{issue.issue_desc}}
<button @click="removeIssue(index)" type="button" class="close" aria-label="Close"><span aria-hidden="true">×</span></button></a>
<!--这里的show_comments属性必须是加载的时候就有的,后面加入的会切换无效-->
<div v-show="issue.show_comments">
<a href="#" class="list-group-item" v-for="(comment,cindex) in issue.comments">{{cindex+1}}. {{comment.content}}
<button @click="removeComment(index,cindex)" type="button" class="close" aria-label="Close"><span aria-hidden="true">×</span></button>
</a>
<div class="input-group">
<input @keyup.enter="saveComment(index,cindex)" type="text" class="form-control" placeholder="new comment" v-model="comment">
<div @click="saveComment(index,cindex)" class="input-group-addon btn">Comment</div>
</div>
</div>
</div>