jQuery给我任何选定的单选按钮的值相同？

<fieldset data-role="controlgroup" data-type="horizontal">
<legend>Business Type</legend>
<input type="radio" name="businessType" value="business" id="business" checked="checked"/>
<label for="business">Business</label>
<input type="radio" name="businessType" value="personal" id="personal"/>
<label for="personal">Personal</label>
</fieldset>

我尝试使用这个jQuery来获取所选单选按钮的当前值,但即使我选择个人,我也会继续将’Business’作为值：

var idd = ($("input:radio[name=businessType]").val());

谢谢

var idd = ($("input:radio[name=businessType]:checked").val());