<li class="cwhite" value="02" id="02" onclick="getQuestionList('02',this);">数学</li>

var subjectCode = $(obj).find(".bd.subject li[class='cwhite active']").val();

这种方法会把02前面的0自动截取

var subjectCode = $(obj).find(".bd.subject li[class='cwhite active']").attr("value");

用attr("value")就不会截取了