I try 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 JavasScript:

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:

Do you have another idea? What am I missing?
====================================

anwser:

One more function prop() that is added in jQuery 1.6, that serves the same purpose.

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