I want to Validate Radio Button List in asp.net using jquery, where I am having radio button list in child page, and I need to show alert box when user never selects any option

Here is the code, which I have tried.

```
$(function(){ 
    $("#<%=btnSave.ClientID %>").click(function(){
          var v=$("#<%=rdTax.ClientID %>input:checked").val(); 
     }); 
});

```