选择一个模态框样式

<!-- Large modal -->
<button type="button" class="btn btn-primary" data-toggle="modal" data-target=".bs-example-modal-lg">Large modal</button>

<div class="modal fade bs-example-modal-lg" tabindex="-1" role="dialog" aria-labelledby="myLargeModalLabel">
  <div class="modal-dialog modal-lg" role="document">
    <div class="modal-content">
      ...
    </div>
  </div>
</div>

其中button按钮中的data-toggle=”modal” data-target=”.bs-example-modal-lg”起到关联的作用，点击该标签，弹出关联的模态框（其中data-target用于查找要关联的模态框是哪个）

示例：将data-toggle=”modal” data-target=”.bs-example-modal-lg”剪切到a标签中，将button标签删除，这样点击”注册”就能弹出模态框

data-target=”.bs-example-modal-lg”对应下面class=”modal fade bs-example-modal-lg”

<a href="#" data-toggle="modal" data-target=".bs-example-modal-lg">注册</a>
<!-- Large modal -->
<div class="modal fade bs-example-modal-lg" tabindex="-1" role="dialog" aria-labelledby="myLargeModalLabel">
    <div class="modal-dialog modal-lg" role="document">
        <div class="modal-content">
        ...
        </div>
    </div>
</div>