if checkbox in gridview is checked then textbox will visible in gridview else invisible using javascript

function ToggleTextBox(checkid,textid) {
            var checkBox = document.getElementById(checkid);
            if (checkBox.checked)
            {
                document.getElementById(textid).style.visibility = 'visible';
            }
            else
            {
                document.getElementById(textid).style.visibility = 'hidden';
            }
        }

<asp:gridview runat="server" id="grid" onrowdatabound="RowDataBoundEvent" xmlns:asp="#unknown">
    <columns>
    <asp:templatefield headertext="Check">
    <itemtemplate>
        <asp:checkbox runat="server" id="cbSelect" checked="false" />
    </itemtemplate>
    </asp:templatefield>
    <asp:templatefield headertext="B1">
    <itemtemplate>
        <asp:textbox id="textBox" runat="server"></asp:textbox>
    </itemtemplate></asp:templatefield>
    </columns>
    </asp:gridview>

protected void Page_Load(object sender, EventArgs e)
       {
           DataTable dt = new DataTable();
           dt.Columns.Add("Name");
           dt.Rows.Add("G");
           dt.Rows.Add("K");
           grid.DataSource = dt;
           grid.DataBind();
       }

       protected void RowDataBoundEvent(object sender, GridViewRowEventArgs e)
       {

           int rowIndex = e.Row.RowIndex;
           if (rowIndex >= 0)
           {
               ((CheckBox)e.Row.FindControl("cbSelect")).Attributes.Add("onclick", "javascript:ToggleTextBox('" +
                       ((CheckBox)e.Row.FindControl("cbSelect")).ClientID + "','"+
                       ((TextBox)e.Row.FindControl("textBox")).ClientID + "')");
           }
       }