如何在c＃中查找subgridview的文本框

Question

任何人都可以建议!!  我有一个嵌套的Gridview，我想要提交按钮上的subgridview的valdate文本框点击我调用javascript但它无法正常工作

function btnSubmit() {
  alert("Hii");

  var findGrid = document.getElementById('<%=GV_CustDetails.ClientID %>');
  var Headers = document.getElementById('th');
  var findPanel2 = Headers.$find('<%=Gv_CustEditDetails.ClientID %>');
  var findTextBox1 = findPanel2.getElementById('<%=Txt_Date.ClientID %>');
  var tt = document.getElementById(findTextBox1);
  var w = tt.value.length;

  tt.style.height = tt.scrollHeight;

  if (!confirm("Are you sure you want to Submit this Record ?"))
    return false;
    
  return true;
}