jquery为下拉框添加option

前台： 
 
    function load_allemployees(employee_type){ 
            var url = "onLoadEmployee.do"; 
            var p_data = "employee_type=" + employee_type; 
            doAjaxSubmit(url, p_data, filSelect); 
    } 
    function filSelect(data){ 
    $("#left_").empty(); 
    var employeeArr = document.getElementById('left_'); 
    for(var i=0;i<data.length;i++) 
    { 
               var op = document.createElement("OPTION"); 
                op.value = data[i].user_id;  
                op.innerHTML =data[i].user_name; 
               employeeArr.appendChild(op); 
  
    } 
    } 
    function doAjaxSubmit(p_url, p_data, p_callback) { 
        $.ajax({ 
            type:"POST", 
            url: p_url, 
            data: p_data, 
            dataType:"json", 
            success: function(data){ 
                p_callback(data); 
            } 
        }); 
    } 

[html]
后台： 
package com.aegon_cnooc.oa.admin.action; 
 
import java.io.PrintWriter; 
import java.util.List; 
import java.util.Map; 
 
import javax.servlet.http.HttpServletRequest; 
import javax.servlet.http.HttpServletResponse; 
 
import net.sf.json.JSONArray; 
import net.sf.json.JSONSerializer; 
import net.sf.json.util.JSONUtils; 
 
import org.apache.struts.action.ActionForm; 
import org.apache.struts.action.ActionForward; 
import org.apache.struts.action.ActionMapping;