我无法弄清楚为什么我一直收到此错误： 未捕获的TypeError：无法读取null的属性'options' getFSREPlist （匿名函数）
该错误引用了这行代码（21）：
document.getElementById(elementidupdate).options.length=0;
奇怪的是它在我刚刚穿上的这个新谷歌地图api之前工作了。此外，它正在拉国家代码“1”并将其放入下拉列表中，但不是省代码“19”。
这是页面上的脚本：
getFSREPlist('1', 'fsrep-search-province', 'CountryID', '19');getFSREPlist('19', 'fsrep-search-city', 'ProvinceID', '3'); request.send(null);
以下是完整档案：
function sack(file) {
this.xmlhttp = null;
this.resetData = function () {
this.method = "POST";
this.queryStringSeparator = "?";
this.argumentSeparator = "&";
this.URLString = "";
this.encodeURIString = true;
this.execute = false;
this.element = null;
this.elementObj = null;
this.requestFile = file;
this.vars = new Object();
this.responseStatus = new Array(2);
};
this.resetFunctions = function () {
this.onLoading = function () {};
this.onLoaded = function () {};
this.onInteractive = function () {};
this.onCompletion = function () {};
this.onError = function () {};
this.onFail = function () {};
};
this.reset = function () {
this.resetFunctions();
this.resetData();
};
this.createAJAX = function () {
try {
this.xmlhttp = new ActiveXObject("Msxml2.XMLHTTP");
} catch (e1) {
try {
this.xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
} catch (e2) {
this.xmlhttp = null;
}
}
if (!this.xmlhttp) {
if (typeof XMLHttpRequest != "undefined") {
this.xmlhttp = new XMLHttpRequest();
} else {
this.failed = true;
}
}
};
this.setVar = function (name, value) {
this.vars[name] = Array(value, false);
};
this.encVar = function (name, value, returnvars) {
if (true == returnvars) {
return Array(encodeURIComponent(name), encodeURIComponent(value));
} else {
this.vars[encodeURIComponent(name)] = Array(encodeURIComponent(value), true);
}
}
this.processURLString = function (string, encode) {
encoded = encodeURIComponent(this.argumentSeparator);
regexp = new RegExp(this.argumentSeparator + "|" + encoded);
varArray = string.split(regexp);
for (i = 0; i < varArray.length; i++) {
urlVars = varArray[i].split("=");
if (true == encode) {
this.encVar(urlVars[0], urlVars[1]);
} else {
this.setVar(urlVars[0], urlVars[1]);
}
}
}
this.createURLString = function (urlstring) {
if (this.encodeURIString && this.URLString.length) {
this.processURLString(this.URLString, true);
}
if (urlstring) {
if (this.URLString.length) {
this.URLString += this.argumentSeparator + urlstring;
} else {
this.URLString = urlstring;
}
}
this.setVar("rndval", new Date().getTime());
urlstringtemp = new Array();
for (key in this.vars) {
if (false == this.vars[key][1] && true == this.encodeURIString) {
encoded = this.encVar(key, this.vars[key][0], true);
delete this.vars[key];
this.vars[encoded[0]] = Array(encoded[1], true);
key = encoded[0];
}
urlstringtemp[urlstringtemp.length] = key + "=" + this.vars[key][0];
}
if (urlstring) {
this.URLString += this.argumentSeparator + urlstringtemp.join(this.argumentSeparator);
} else {
this.URLString += urlstringtemp.join(this.argumentSeparator);
}
}
this.runResponse = function () {
eval(this.response);
}
this.runAJAX = function (urlstring) {
if (this.failed) {
this.onFail();
} else {
this.createURLString(urlstring);
if (this.element) {
this.elementObj = document.getElementById(this.element);
}
if (this.xmlhttp) {
var self = this;
if (this.method == "GET") {
totalurlstring = this.requestFile + this.queryStringSeparator + this.URLString;
this.xmlhttp.open(this.method, totalurlstring, true);
} else {
this.xmlhttp.open(this.method, this.requestFile, true);
try {
this.xmlhttp.setRequestHeader("Content-Type", "application/x-www-form-urlencoded")
} catch (e) {}
}
this.xmlhttp.onreadystatechange = function () {
switch (self.xmlhttp.readyState) {
case 1:
self.onLoading();
break;
case 2:
self.onLoaded();
break;
case 3:
self.onInteractive();
break;
case 4:
self.response = self.xmlhttp.responseText;
self.responseXML = self.xmlhttp.responseXML;
self.responseStatus[0] = self.xmlhttp.status;
self.responseStatus[1] = self.xmlhttp.statusText;
if (self.execute) {
self.runResponse();
}
if (self.elementObj) {
elemNodeName = self.elementObj.nodeName;
elemNodeName.toLowerCase();
if (elemNodeName == "input" || elemNodeName == "select" || elemNodeName == "option" || elemNodeName == "textarea") {
self.elementObj.value = self.response;
} else {
self.elementObj.innerHTML = self.response;
}
}
if (self.responseStatus[0] == "200") {
self.onCompletion();
} else {
self.onError();
}
self.URLString = "";
break;
}
};
this.xmlhttp.send(this.URLString);
}
}
};
this.reset();
this.createAJAX();
}
var ajax = new Array();
function getFSREPlist(sel, elementidupdate, fsrepvariable, currentvalue) {
if (sel == '[object]' || sel == '[object HTMLSelectElement]') {
var FSREPID = sel.options[sel.selectedIndex].value;
} else {
var FSREPID = sel;
}
document.getElementById(elementidupdate).options.length = 0;
var index = ajax.length;
ajax[index] = new sack();
ajax[index].requestFile = 'http://www.cabcot.com/wp-content/plugins/firestorm-real-estate-plugin/search.php?' + fsrepvariable + '=' + FSREPID + '&cvalue=' + currentvalue;
ajax[index].onCompletion = function () {
ElementUpdate(index, elementidupdate)
};
ajax[index].runAJAX();
}
function ElementUpdate(index, elementidupdate) {
var obj = document.getElementById(elementidupdate);
eval(ajax[index].response);
}
答案 0 :(得分：1)
加载DOM时应调用getFSREPlist。我跑了
document.getElementById('fsrep-search-province').options.length=0
来自chrome´s console。页面仍在加载并导致同样的错误。
