using checkbox as radio button

Question

I am looking for a way for users to select one of the two options (strength or weakness) for a list of qualities.

for eg:

                   strength     weakness  not applicable
1. Communication 
2. Punctuality
   ...

Radio button lets me select either a strength or weakness. However, I want the user to check only those qualities that apply and if a user accidentally selects a quality there is no way to undo the selection for a radio button unless there is a third radio button called not applicable or have the user re-enter the page. I was wondering if there is a way to be able to get the flexibility of a checkbox (check / uncheck) in addition to disabling or enabling the other checkbox when one of them is checked or unchecked instead of using three radio buttons.

I don't think I have seen this behavior before so wondering if there is a more elegant way of doing this. I am open to other ideas to get the same functionality. Using a checkbox as radio button was just a thought.

thanks much.

Answer 1

Solution based on javascript

function SetSel(elem)
{
  var elems = document.getElementsByTagName("input");
  var currentState = elem.checked;
  var elemsLength = elems.length;

  for(i=0; i<elemsLength; i++)
  {
    if(elems[i].type === "checkbox")
    {
       elems[i].checked = false;   
    }
  }

  elem.checked = currentState;
}​

<input type="checkbox" class="chkclass" onclick="SetSel(this);" />
<input type="checkbox" class="chkclass" onclick="SetSel(this);" />
<input type="checkbox" class="chkclass" onclick="SetSel(this);" />
<input type="checkbox" class="chkclass" onclick="SetSel(this);" />

Working Demo

Solution based on jQuery

$(function(){
    $("input:checkbox.chkclass").click(function(){
      $("input:checkbox.chkclass").not($(this)).removeAttr("checked");
      $(this).attr("checked", $(this).attr("checked"));    
    });
});​

<input type="checkbox" class="chkclass" />
<input type="checkbox" class="chkclass" />
<input type="checkbox" class="chkclass" />
<input type="checkbox" class="chkclass" />

Working Demo

Answer 2

You should not use checkboxes as radio buttons (or vice-versa): this is inconsistent with the user's mental model, so it confuses people.

This is a problem with no ideal solution, but your initial suggestion of having a "not applicable" option as part of a group of 3 radio buttons is fairly common. If you pre-select the "not applicable" option by default and perhaps de-emphasize it visually (eg. gray it out) then from the user's point of view it will be almost as if there are only 2 options, but they can recover if they accidentally select one and want to "unselect" it.

Answer 3

this is correct form, "checked" is a proprietary and not attribute

   $(function(){
      $("input:checkbox.chkclass").each(function(){
        $(this).change(function(){
            $("input:checkbox.chkclass").not($(this)).prop("checked",false);
            $(this).prop("checked", $(this).prop("checked"));       
        });   
      });
    });