java脚本实现下拉框和文本框的数据交换

          




   <script language="javascript">...


                              function change(va)




                              ...{


                                   if(va.value==<%=a%>)


                                      str=' <input name="cnum" type="text" id="cnum" value="'+va.value+'" size="15" ><br><input name="course" type="text" size="15" value="填写新课程名" >';


                                    else


                                    str=' <input name="cnum" type="text" id="cnum" value="'+va.value+'" size="15" > <input type="hidden" name="course" value=" ">';


                                    


                                    window.show.innerHTML=str;


                              }


                              </script>  


<table>


                           <tr>


                              <td width="48%" align="center">课程号</td>


                              <td width="52%" id="show">     </td>


                            </tr>


</table>




 <select name="select4" onChange="change(this)">


                                <option   selected>选择课程</option>


                                <option value="<%=a%>" >添加新课</option>


                             




                                  <%... for (int i = 0; i < length; i++){ %>


                                   <option  value="<%=titlelist3[i]%>" ><%=titlelist[i]%></option>


                             <%}%>


                                    </select>