请教 此JS 代码 那里出现了有关问题大家帮忙看看

请问 此JS 代码 那里出现了问题大家帮忙看看！
现在是 json  其他的都能或得到 就 那个参与人的 input name="px_chanyure" id="btnEdit1" 获取不到值 只能获取,如 张三,李四,王二   获取到的就是,,, 三个逗号

<div id="form1">

<table width="800" border="0" align="center" cellpadding="0" cellspacing="1" bgcolor="#CCCCCC" id="tableId">

  <tr>

    <td height="32" colspan="6" bgcolor="#5d7bb7">&nbsp;&nbsp;&nbsp;<span class="STYLE3">培训记录</span></td>

  </tr>

  <tr>

    <td width="70" height="30"><div align="center">培训名称</div></td>

    <td width="133">&nbsp;<input name="px_name" class="mini-textbox" id="px_name" style="width:120px;" required="true"/></td>

    <td width="79"><div align="center">开始时间</div></td>

    <td width="192">&nbsp;<input name="px_kssj" class="mini-datepicker" id="px_kssj" style="width:120px;"/></td>

    <td width="102"><div align="center">结束时间</div></td>

    <td width="217">&nbsp;<input name="px_jssj" class="mini-datepicker" id="px_jssj" style="width:120px;"/>

  </tr>

  <tr>

    <td height="30"><div align="center">课程分类</div></td>

    <td>&nbsp;<input id="px_pxfs"  name="px_kcfl"  class="mini-combobox" style="width:120px;" valuefield="id"  url="../include/Config_jd.jsp?hr=chaxun" value="<%=request("tjlb")%>"  required="true"  textfield="text"   /></td>

    <td><div align="center">培训方式</div></td>

    <td>&nbsp;<input id="px_pxfs"  name="px_pxfs"  class="mini-combobox" style="width:120px;" valuefield="id"  url="../include/Config_jd.jsp?hr=chaxun" value="<%=request("tjlb")%>"  required="true"  textfield="text"   /></td>

    <td>&nbsp;</td>

    <td>&nbsp;</td>

  </tr>

  <tr>

    <td height="30"><div align="center">参 与 人</div></td>

    <td colspan="5">&nbsp;

           <input name="px_chanyure" id="btnEdit1" class="mini-buttonedit" onbuttonclick="onButtonEdit" style="width:510px;"  />


    

  </tr>

  <tr>

    <td height="30">&nbsp;</td>

    <td colspan="5">&nbsp;&nbsp;<a class="mini-button" iconCls="icon-save" onClick="submitForm()" />提交保存</a></td>

  </tr>

</table>

</div>

    <script type="text/javascript">

        mini.parse();

        function onButtonEdit(e) {

            var btnEdit = this;

            mini.open({                

                url: bootPATH + "../select_renyuan.jsp",    

                showMaxButton: true,

                title: "选择参与人员",

                width: 650,

                height: 380,

                onload: function () {

                    var iframe = this.getIFrameEl();

                    iframe.contentWindow.SetData(null);

                },

                ondestroy: function (action) {                    

                    if (action == "ok") {

                        var iframe = this.getIFrameEl();