javascript中this.formObj 传递不过去，变成了TypeError: this.formObj is undefined

Question

var searchForm = {
    formObj: null,
    jsonUrlAgent: false,
    filter: null,
    ajaxSelect: null,
    regAjaxSelect: function (json) {
        this.ajaxSelect = json;
    },
    init: function (formName, filter) {
        this.formObj = document.forms[formName];
        this.filter = filter;

        if (!this.formObj) {
            alert('未在DOM中找到form元素[name=' + formName + ']');
            return false;
        }

        //给select input赋值查询条件
        if (this.filter) {
            for (var i in this.filter) {
                if (/AgentId(P|I)/.test(i) || !this.filter[i]) {
                    continue;
                }

                if (/^(input|select)$/i.test(this.formObj[i].tagName)) {
                    this.formObj[i].value = this.filter[i];
                }
            }
        }

        //先给 ajaxSelect 注册的元素获取AJAX数据
        if (this.ajaxSelect) {
            for (var k in this.ajaxSelect) {
                if (this.formObj[k]) {
                    //已选择的值
                    if (typeof this.filter[k] == 'undefined') {
                        this.filter[k] = '';
                    }

                    selectNull(this.formObj[k].id);
                    selectChange(this.ajaxSelect[k][0], this.formObj[k].id, this.filter[k], this.ajaxSelect[k][1], this.ajaxSelect[k][2]);
                }
            }
        }

        //再处理层级关系的 AgentIdP AgentIdI
        //设定有AgentIdP,一定有AgentIdI
        if (this.formObj['AgentIdP']) {

            if (this.jsonUrlAgent) {
                //已手动定义了JSON地址
            } else if (typeof jsonUrl == 'object' && typeof jsonUrl.myAgent == 'string') {
                this.jsonUrlAgent = jsonUrl.myAgent;//全局中定义了 jsonUrl
            } else {
                alert('未配置的 agent 请求JSON 地址！');
                return false;
            }

            if (!this.filter['AgentIdP']) {
                this.filter['AgentIdP'] = '';
            }

            console.log(this.formObj);//有

            selectNull(this.formObj['AgentIdP'].id);
            selectChange(this.jsonUrlAgent, this.formObj['AgentIdP'].id, this.filter['AgentIdP'], 'AGENTID', 'AGENTNAME', this.reqAgentIdI);
        }
    },
    reqAgentIdI: function () {
        console.log(this.formObj);//到了这里就null了
        if (this.filter && this.filter['AgentIdI']) {
            selectNull(this.formObj['AgentIdI'].id);
            selectChange(this.jsonUrlAgent + this.filter['AgentIdP'], this.formObj['AgentIdI'].id, this.filter['AgentIdI'], 'AGENTID', 'AGENTNAME');
        }
    }
}

用法

HTML部分

<form method="GET" action="" id="formSearch" name="formSearch">
  <table width="100%" border="0">
    <tr>
      <td width="30%">渠道选择：
        <select name="AgentIdP" id="AgentIdP" style="width:100px" onchange="selectNull('AgentIdI');selectChange(jsonUrl.myAgent+this.value,'AgentIdI','','AGENTID','AGENTNAME')">
          <option value="1">百度</option>
        </select>
        <select name="AgentIdI" id="AgentIdI" style="width:100px">
          <option>--</option>
        </select>


            游戏名称：
            <input name="GameName" type="text" id="GameName" style="width:100px" /></td>
        <td width="18%">
            文件名：
            <input name="FileName" type="text" id="FileName" style="width:100px" /></td>
      <td width="16%">
        <input type="submit" name="button" id="button" value="查找" style="width:80px; height:40px"/>
        <input type="button" name="button2" id="button2" value="显示全部" style="width:80px; height:40px" onclick="location='http://localhost/index.php/gamedownurl/lst'"/></td>
    </tr>
  </table>
  </form>

用到的函数selectNull 与 selectChange

/**
 * @author  fzb
 * @description 清空select数据的所有option
 * @param objId
 */
function selectNull(objId) {
    var selObj = document.getElementById(objId);
    selObj.options.length = 0;
    selObj.options[0] = new Option(' 请选择 ', ' ');
    selObj.options[0].className = 'dft-empty';
}

/**
 * @author fzb
 * @description 用于与selectNull配合自动分析返回JSON数据生成select option值
 *
 * @param ajaxUrl
 * @param subId
 * @param dftValue
 * @param IdKeyName
 * @param TxtKeyName
 * @param callbackFunc
 * @returns {boolean}
 */
function selectChange(ajaxUrl, subId, dftValue, IdKeyName, TxtKeyName, callbackFunc) {
    var subObj = document.getElementById(subId);
    if (!subObj) {
        alert('不存在的子对象！');
        return false;
    }

    $.getJSON(ajaxUrl, function (json) {

        subObj.options.length = 0;
        subObj.options[0] = new Option(' 请选择 ', '');
        subObj.options[0].className = 'dft-empty';

        var j = 1;
        for (var i in json) {
            subObj.options[j] = new Option(json[i][TxtKeyName], json[i][IdKeyName]);
            j++;
        }

        if (dftValue) {
            subObj.value = dftValue;
        }

        if (callbackFunc) {
            callbackFunc();
        }
    });
}
//-----------------------------------------------------------

javascript部分

<script>
var jsonUrl = {"myAgent":"http:\/\/localhost\/index.php\/agent\/jsonMyAgent?pid=","myGame":"http:\/\/localhost\/index.php\/game\/jsonMyGame"};

var filter = {"GameName":"","FileName":"","AgentIdP":"1001","AgentIdI":"1003"};
var ajaxSelect = {
   'GameId': [jsonUrl.myGame,'GAMEID','GAMENAME']
};
searchForm.regAjaxSelect(ajaxSelect);
searchForm.init('formSearch',filter);
</script>

结果到了 searchForm.reqAgentIdI 就提示报错了

TypeError: this.formObj is undefined
selectNull(this.formObj['AgentIdI'].id);

http://jsbin.com/boriciro/1/

---

关闭重复问题： javascript 的 callback 是否有问题，会导致对象无法传递 - SegmentFault --依云

Answer 1

jsonUrl.myGame 无法识别

我随便找了个字符串替代了这个变量结果显示。
未配置的 agent 请求JSON 地址！

Answer 2

因为this指向的是window，所以this.formObj中就是window.formObj，不存在