CODEWITHSUNDEEP
javascriptjqueryasp.net
user123456789
user123456789

Reputation: 2004

javascript error: Cannot read property 'options' of null

I have a GridView that has a column with a textbox where the user can enter a value and a column with a dropdownlist. If the user enter a values that is not equal to 1 in the textbox, they must select a value from the dropdownlist. The default value in the DDL is "Select" which is just an empty value that was coded in: ddlReasons.Items.Insert(0, new ListItem("Select"));. The DDL is created dynamically but select will always be the default value. 

 function UpdateSerialQtyRcvd(SerNoID, QtyRcvd) {
        if (QtyRcvd != 1) {
            var ddl = document.getElementById("ddlReasons");
            var selectedValue = ddl.options[ddl.selectedIndex].value;
            if (selectedValue == "Select") {
                alert("Must select reason");
            }

        }
        else {
            PageMethods.UpdateSerialQtyRcvdUserControl(SerNoID, QtyRcvd, OnUpdateSuccess, OnUpdateFail);
        }
    }

If the user enters a value that is not 1 then I need to check what value is in the DDL. If "Select" is the value I need the user to select something else in the DDL but I am getting this error on the line var selectedValue = ddl.options[ddl.selectedIndex].value;

Uncaught TypeError: Cannot read property 'options' of null

Code for dropdownlist:

<asp:TemplateField HeaderText="Reason">
 <ItemTemplate>
  <asp:DropDownList ID="ddlReasons" runat="server" class="ReasonDDL" ></asp:DropDownList>
 </ItemTemplate> 
</asp:TemplateField>

Upvotes: 1

Views: 11953

Answers (2)

Parthipan Natkunam
Parthipan Natkunam

Reputation: 784

One more way to do it using JQuery :

var ddlReason = $("[id*=ddlReasons]");
var selectedValue = ddlReason.val();

Upvotes: 0

Christian Phillips
Christian Phillips

Reputation: 18769

You'll need to get the ClientId...

Javascript:

var ddl = document.getElementById("<%=ddlReasons.ClientID%>");

JQuery:

var ddl = $('#<%=ddlReasons.ClientID%>');

Check out the MSDN documentation on how to access the Client ID and the different settings.

Upvotes: 1

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