SOURCE

// 隐藏modal
    $('body').on('click', '[data-dismiss="modal"]', function() {
        $(this).parents('.modal').addClass('hide');
        // $('.modal').modal('hide');
    });

    // 显示modal
    $('body').on('click', '[data-toggle="modal"]', function() {
        var target = $(this).data('target');
        $(target).removeClass('hide');
        // $('.modal').modal('hide');
    });

 <div class="hw-iframe">
    <!-- 顶部标题 -->
    <div class="hw-header-wrapper">
        <div class="hw-header">
            <div class="hw-header__item--left">
                modal框演示
            </div> 
        </div>
    </div>

    <div class="hw-btn-group"> 
        <button class="hw-btn--normal" id="modal-btn" data-toggle="modal" data-target="#img-modal"> modal </button>
    </div>
</div>

<div class="modal hide" id="img-modal">
    <div class="modal-mask"></div>
    <div class="modal-content">
        <div class="modal-header">
            <i class="iconfont" data-dismiss="modal">&#xe63d;</i>
            <div class="modal-title">提示</div>
        </div>
        <div class="modal-body">
            这是一段信息
        </div>
        <div class="modal-footer">
            <button class="hw-btn--normal" data-dismiss="modal">确定</button>
            <button class="hw-btn--default" data-dismiss="modal">取消</button>
        </div>
    </div>
</div>