js 获取复选框所在行

document.onclick = function(e) {     // 兼容 event 和 target     e = e || window.event;     var target = e.target || e.srcElement;     // 确认是 checkbox     if(target.tagName.toLowerCase() === "input"         && target.type === "checkbox") {         // 获取行列键值         var row_num = target.parentNode.parentNode.rowIndex;         var col_num = target.parentNode.cellIndex;         // 输出         alert(row_num + " " + col_num);     } };