make control visible based off other control value

I have an asp.net application and Im trying to accomplish the following.

For arguments sake lets say I have a <asp:button> <asp:dropdownlist> and a <asp:label>
When I click the button I want to check the dropdownlist for selectedvalue > 0 and make the label visible if true

I have save code that runs on the OnClick event of the button already but if the selecteditem.value of a dropdown =0 I want the save code not to run and just show a label that Im using as a fieldvalidator(user must select a drop down item)

I tried to create a function that would with OnClientClick but obviously didnt do it correctly...

Any help would be appreciated!

ASP.NETVisual Basic.NETJavaScript

Last Comment

jknj72

8/22/2022 - Mon

Ryan Chong

4/11/2017

I tried to create a function that would with OnClientClick but obviously didnt do it correctly...

so first, you need to decide if you want to do it in Server Side or Client Side?

you may also post your existing codes so we can further provide the advice.

jknj72

4/12/2017

ASKER

I am open to whatever works. I have an OnClick event already so I am having trouble getting the client side to run and return false so it doesnt have to run the server code but it wasnt working.

Client side

    function DisplayValidator() {
        
        var ddl = document.getElementById('ddlRejectedBy').value;
        //alert(ddl);
        var lbl = document.getElementById('lblValidator');   
        //alert(lbl);

        if (ddl == "0")
            lbl.style.display = "";
        else
            lbl.style.display = "none";
        return;

    }

//button call to function
<asp:Button ID="btnOkTest" runat="server" BackColor="#46A3FF" Font-Bold="True" Font-Size="Medium" ForeColor="GrayText" Height="30px" OnClientClick="return DisplayValidator();" OnClick="btnOkTest_Click" Text="Ok" Width="100px" Enabled="false" />