为什么要用js呢，不是这样也可以吗

<button type="button" class="btn btn-primary btn-lg" data-toggle="modal" data-target="#myModal">弹窗</button>

<div class="modal" id="myModal">

<div class="modal-dialog">

<div class="modal-content">

<div class="modal-header">

<button class="close" type="button" data-dismiss="modal">

<span>&times;</span><span class="sr-only">关闭弹窗</span>

</button>

<h4 class="modal-title" id="myModalLabel">这是弹窗</h4>

</div>

<div class="modal-body">

这是弹窗内容！

</div>

<div class="modal-footer">

<button class="btn btn-default" type="button" data-dismiss="modal">关闭</button>

<button class="btn btn-primary" type="button" >保存</button>

</div>

</div>

</div>

</div>