javascript 未捕获的类型错误：无法读取 null 的属性“选项”

Uncaught TypeError: Cannot read property 'options' of null

提问by Chris Allington

I cannot figure out why I keep getting this error: Uncaught TypeError: Cannot read property 'options' of null getFSREPlist (anonymous function)

我不知道为什么我一直收到这个错误：Uncaught TypeError: Cannot read property 'options' of null getFSREPlist (anonymous function)

The error is referencing this line of code (21):

错误引用了这行代码 (21)：

document.getElementById(elementidupdate).options.length=0;

What is weird is that it was working prior to this new google map api I just put on. Also, it is pulling the country code "1" and putting it in the drop down, but not the province code "19".

奇怪的是，它在我刚刚安装的这个新的谷歌地图 api 之前就可以工作了。此外，它正在拉动国家代码“1”并将其放入下拉列表中，而不是省代码“19”。

Here is the on page script:

这是页面脚本：

getFSREPlist('1', 'fsrep-search-province', 'CountryID', '19');getFSREPlist('19', 'fsrep-search-city', 'ProvinceID', '3');           request.send(null);

Here is the full file:

这是完整的文件：

   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);
}

回答by Jaime Guaman

You should call getFSREPlistwhen DOM is loaded. I ran

您应该getFSREPlist在加载 DOM 时调用。我跑了

document.getElementById('fsrep-search-province').options.length=0

from chrome′s console. while page was still loading and caused that same error.

从chrome′s console. 而页面仍在加载并导致相同的错误。

http://i.imgur.com/GBFizq1.png

http://i.imgur.com/GBFizq1.png