button按一下运行了两次

        <div class="mui-button-row">  
            <button id="orderdetailadd" type="button" class="mui-btn mui-btn-danger" disabled="disabled" style="display:inline-block;">增加明细</button>&nbsp;&nbsp;&nbsp;  
            <button id="ordersave" type="button" class="mui-btn mui-btn-primary" disabled="disabled" style="display:inline-block;">保存</button>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;  
            <button id="orderadd" type="button" class="mui-btn mui-btn-danger" disabled="disabled" style="display:inline-block;">新增</button>  
        </div>  

增加监听事件：
document.getElementById("orderdetailadd").addEventListener('tap', function() {
DetailCount = DetailCount + 1;
mui.toast("增加明细" + DetailCount );

    });  

会有两次显示，并且DetailCount 也是增加了的，如显示 增加明细3 和 增加明细4