bootstrap模态框的使用

html代码：
 

<!--模态框-->
<div class="modal fade addFirstCategory">
    <div class="modal-dialog modal-sm">
        <div class="modal-content">
            <div class="modal-header">
                <button type="button" class="close" data-dismiss="modal" ><span >&times;</span></button>
                <h4 class="modal-title">添加分类</h4>
            </div>
            <div class="modal-body">
                <div class="form-group">
                    <input type="text" class="form-control" placeholder="请输入一级分类名称" name="firstCategoryName">
                </div>
            </div>
            <div class="modal-footer">
                <button type="button" class="btn btn-default" data-dismiss="modal">取消</button>
                <button type="button" class="btn btn-primary">保存</button>
            </div>
        </div>
    </div>
</div>

js代码：
 

 //模态框初始化
        $('#addBtn').on('click', function () {
            // show  或 hide
            $('.addFirstCategory').modal('show')
        })