I have ASP.Net page where i am calling a JavaScript function like this:
Enter server name: <asp:TextBox ID="txt_name" runat="server"></asp:TextBox>
<asp:Button ID="btn_view" runat="server" OnClick="View_btn_click" OnClientClick="return AlertOnGo('View Configuration',document.getElementById('<%= txt_name.ClientID %>').value)" Text ="GO!" />
But on clicking the GO button, i am getting the following error:
JavaScript runtime error: Unable to get property 'value' of undefined or null reference
On viewing the rendered code for the button:
<input type="submit" name="btn_view" value="GO!" onclick="return AlertOnGo('View Configuration',document.getElementById('<%= txt_name.ClientID %>').value);" id="btn_view" />
It is not putting the appropriate ClientID. I tried setting the CLientIDMode to static for the test box, yet no help.
This question is similar to this unanswered question.
There are a few solutions to this problem.
One of the simpler would be to move the name into a JavaScript variable since the problem only occurs within the control when trying to evaluate txt_name.ClientID inside the OnClientClick attribute of an ASP.NET control.
<script>
var txtName = '<%= txt_name.ClientID %>';
</script>
Enter server name: <asp:TextBox ID="txt_name" runat="server"></asp:TextBox>
<asp:Button ID="btn_view" runat="server" OnClick="View_btn_click"
OnClientClick="return AlertOnGo('View Configuration',
document.getElementById(txtName).value)" Text ="GO!" />