mui如何取元素屬性的值

<ul id="OA_task_1" class="mui-table-view">
<li class="mui-table-view-cell">
<div class="mui-slider-right mui-disabled">
<a class="mui-btn mui-btn-blue" id="bianji" val='id1'>編輯</a>
<a class="mui-btn mui-btn-red" id="shanchu" val='id1'>刪除</a>
</div><div class="mui-slider-handle">姓名1</div>
</li>
</ul>
<script>
$('#OA_task_1').on('tap', '#shanchu', function(event) {
                        var aa=this.val;//這里直接用this獲取
                        console.log("id是"+aa);//獲取到為undefined
                        //mui
                        var elem = this;
                        var li = elem.parentNode.parentNode;
                        mui.confirm('確認(rèn)刪除該條記錄？', '溫馨提示', btnArray, function(e) {
                            if (e.index == 0) {
                                li.parentNode.removeChild(li);
                            } else {
                                setTimeout(function() {
                                    $.swipeoutClose(li);
                                }, 0);
                            }
                        });
                    });
</script>