How to check a radio button with jQuery

Question

I was trying to check a radio button with jQuery. Here's my code:

<form> 
          <div id='type'> 
                  <input type='radio' id='radio_1' name='type' value='1' /> 
                  <input type='radio' id='radio_2' name='type' value='2' /> 
                  <input type='radio' id='radio_3' name='type' value='3' /> 
            </div> 
</form>

And the JavaScript:

jQuery("#radio_1").attr('checked', true);

Doesn't work:

jQuery("input[value='1']").attr('checked', true);

Doesn't work:

jQuery('input:radio[name="type"]').filter('[value="1"]').attr('checked', true);

Doesn't work:

Does anyone have another idea? I am unable to understand what am I missing?

Answer 1

For versions of jQuery equal or above (>=) 1.6, use:

$("#radio_1").prop("checked", true);

For versions prior to (<) 1.6, use:
 

$("#radio_1").attr('checked', 'checked');

One could also call click() or change() on the radio button afterwards.