$.each(jsonarray, function(i, obj) {
     troptions += "<tr data-sort-field-ftime=\""+obj.paiming+"\">";     
     troptions += "<td>"+(Number(obj.cdsPrem)/unitnow).toFixed(dotnow)+"</td>";
     troptions += "<td>"+(Number(obj.cdjPrem)/unitnow).toFixed(dotnow)+"</td>";
     troptions += "<td>"+(Number(obj.sumPrem)/unitnow).toFixed(dotnow)+"</td>";
     troptions += "<td>"+obj.paiming+"</td>";
     troptions += "</tr>";
   });

//排序处理
 function changepm(){
  var sortType=$("#pm").val();
  var $trList = $("#ta tbody > tr");//获取现有tr对象
  //冒泡排序  
  for (var i = 0; i < $trList.length - 1; i++) {
   for (var j = 0; j < $trList.length - 1 - i; j++) {
    var value1 = parseInt($trList[j].attributes["data-sort-field-ftime"].nodeValue); 
    var value2 = parseInt($trList[j + 1].attributes["data-sort-field-ftime"].nodeValue);
    if (sortType === "asc" ? value1 > value2 : value1 < value2) {
     var $temp = $trList[j];
     $trList[j] = null;
     $trList[j] = $trList[j + 1];
     $trList[j + 1] = null;
     $trList[j + 1] = $temp;
    }
   }
  }      
  //返回排序后的tr集合
  //将原来的tr清空，再将排序后的tr插入到table的dom中
  console.log($trList);
  $trList.appendTo($("#ta > tbody").empty());
 }