如何改成jQuery写法，小白求帮忙。

Question

        $("#search").bind("click",function(){
            if(document.getElementById("keyword").value!=""){//姓名框有输入内容
                var q_mpostid=document.getElementById("q_mpostid");//中类下拉框
                var q_spostid=document.getElementById("q_spostid");//小类下拉框
                var q_capgrade=document.getElementById("q_capgrade");//能力等级
                //下拉框数组
                var q_mpostids=q_mpostid.getElementsByTagName("option");
                var q_spostids=q_spostid.getElementsByTagName("option");
                var q_capgrades=q_capgrade.getElementsByTagName("option");
                q_mpostids[0].selected=true;
                q_spostids[0].selected=true;
                q_capgrades[0].selected=true;
            }
            reloadPage();
        });

Answer 1

$("#q_mpostid option")[0].attr("selected", true);
$("#q_spostid option")[0].attr("selected", true);
$("#q_capgrade option")[0].attr("selected", true);