Uncaught Type Error: Cannot read property 'rows' of null at Search_Gridview

I want to search Record id form asp.net Gridview, I have used a textbox and create a function in javascript and then search value from the client side. I am facing this problem I have shared error and code.

ERROR

APIData:119 Uncaught TypeError: Cannot read property 'rows' of null
at Search_Gridview (APIData:119)
at HTMLInputElement.onkeyup (APIData:229)

<asp:TextBox ID="txtSearchBox" runat="server" Font-Size="20px" onkeyup="Search_Gridview(this,'GridView1')"></asp:TextBox>

<asp:GridView ID="GridView1" runat="server" CellPadding="10" Width="500px">
</asp:GridView>

function Search_Gridview(strKey, gvdata) {
  var strData = strKey.value.toLowerCase().split(" ");
  var tblData = document.getElementById("gvdata");    
  var rowData;

  for (var i = 1; i < tblData.rows.length; i++) {
    rowData = tblData.rows[i].innerHTML;
    var styleDisplay = 'none';
    for (var j = 0; j < strData.length; j++) {
      if (rowData.toLowerCase().indexOf(strData[j]) >= 0)
        styleDisplay = '';
      else {
        styleDisplay = 'none';
        break;
      }
    }
    tblData.rows[i].style.display = styleDisplay;
  }
}