请问如何用jquery获取下面的html中被选中的单选按钮的值?
<input type="radio" id="site_categroy_18156" name="site_categroy_id" value="18156" /> <label for="site_categroy_18156">.NET新手区</label> <input type="radio" id="site_categroy_108699" name="site_categroy_id" value="108699" /> <label for="site_categroy_108699">ASP.NET</label> <input type="radio" id="site_categroy_108700" name="site_categroy_id" value="108700" /> <label for="site_categroy_108700">C#</label> <input type="radio" id="site_categroy_108716" name="site_categroy_id" value="108716" /> <label for="site_categroy_108716">WinForm</label>
$('input:radio[name="site_categroy_id"]:checked').val();
$("input[name=site_categroy_id]:checked").val()