JavaScript - radio button validation

[sunsolaris2000]

A list of courses is displayed and user has to select 1, so I used radio buttons. The course list vary from one student to another.

If I have more than 1 courses displayed and user selects one, everything is ok, but if I display 1 course, the test is JS seems to not be right...

Validate if radio button(a course) was checked:

function validate2() {
                //validate radio buttons(if a course is selected)
                var n = document.entry2.courses.length;
                ok = 0;
 
                for(var i = 0; i < n; i++){
                    if(document.entry2.courses[i].checked){
                        ok++;
                        break;
                    }
                }            
 
                if((document.entry2.ex.checked == true)||
                  (document.entry2.sem.checked == true)||
                  (document.entry2.lab.checked == true)||
                  (document.entry2.pro.checked == true)){
                    ok++;
                }
 
                if(ok == 2){
                    return true;
                }else{
                    alert("Please select 1 course and at least 1 activity! ok=" +ok);
                    return false;
                }                
            } 
 

<form action="Result.jsp" method="post" name="entry2" onSubmit = "return validate2()">
 
                  Please choose a course from the ones
                  <br> where student is assigned:<br><br>
 
               ...............
 
                <table border="1" cellspacing="1" cellpadding="8" bgcolor= #EBDDE2> 
 
                 <%
                 Iterator<String> i = cs.iterator();
                String sCourse = null;
 
                 while(i.hasNext()){
                   sCourse = i.next();    
                %>
 
                <tr>
                  <td><%= sCourse %><input type= "radio" name= "courses" value="<%= sCourse %>"></td>
                </tr>
 
                <%}%>
            </table>

ok is not becoming 1 at the for loop if there is 1 course only
Thank you!

[gits]

in case that this one option isn't 'checked' then it will not be counted - or what is the exact problem? can you post the html as it turns out in the browser instead of the jsp-page? may be you want to auto-select the option when there is only one available?

[sunsolaris2000]

ok must be 2 for the form to be submitted.
And I get ok=1 only when I have 1 course.