JavaScript - Validation Function

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ASP.NET

Javascript

validation

I need to validate a DropDownList in an ASP.NET project and am trying to use JavaScript even though I have never used it before.
I'm using the following ASP declaration and code JavaScript:

ASP declaration:

<asp:DropDownList ID="ddl1" runat="server" onprerender="ddl1_PreRender" ValidationGroup="AddNewCollection">
</asp:DropDownList>
<asp:CustomValidator ID="CustomValidator1" runat="server" ErrorMessage="Choose Type!"
ControlToValidate="ddl1"  ForeColor="Red" ValidationGroup="AddNewCollection" ClientValidationFunction="clientSideCheckValue"></asp:CustomValidator>>

JavaScript code:

<script type="text/javascript">
    function clientSideCheckValue(source, args) 
     {
       var result1 = args.Value;   
       var rsult2 = document.getElementById("ddl1").value;
       if (result2 == null) {
          args.IsValid = false;
          return true;
       }
      args.IsValid = true;
    }
</script>

I have two questions about code mentioned above:

1.Why when I'm printing this row's code var result1 = args.Value; intelisense dosen't give me option to choose "Value" extension.

2.At this line of JavaScript code var rsult2 = document.getElementById("ddl1").value;

I get this error message Microsoft JScript runtime error: Object required.Have you got any idea why i meet this problem and how can i fix it?

Thank you in advance.