Ionic运行时错误无法读取null的属性"toLowerCase“

Question

我试图通过“离子服务”查看一个应用程序，但我得到了这个错误。我看过其他主题，但从未见过运行时错误。我尝试了他们所有的解决方案，但我仍然会有相同的错误页面。这是我所看到的：

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老实说，我不是这个应用程序的程序员，但我是从商店买的。但是，我知道一些在这里和那里。如果有一个简单的解决方案来解决这个问题，那就太棒了！

第一个错误链接指向此处：

_this.initialData();
var operating_system = '';
var admob = {};
if (_this.device.platform.toLowerCase() == 'android') {
     operating_system = 'android';
     admob = {
         banner: settings['admob_android_banner'],
         interstitial: settings['admob_android_interstitial']
     };
 }

第二个错误链接指向这里：

SafeSubscriber.prototype.__tryOrUnsub = function (fn, value) {
    try {
        fn.call(this._context, value);
    }
    catch (err) {
        this.unsubscribe();
        throw err;
    }
};

第三个错误指向这里：

SafeSubscriber.prototype.next = function (value) {
    if (!this.isStopped && this._next) {
        var _parentSubscriber = this._parentSubscriber;
        if (!_parentSubscriber.syncErrorThrowable) {
            this.__tryOrUnsub(this._next, value);
        }
        else if (this.__tryOrSetError(_parentSubscriber, this._next, value)) {
            this.unsubscribe();
        }
    }

第四个错误指向这里：

Subscriber.prototype._next = function (value) {
    this.destination.next(value);
};

第五个错误指向这里：

var /** @type {?} */ response = new Response(responseOptions);
    response.ok = isSuccess(status);
        if (response.ok) {
            responseObserver.next(response);
            // TODO(gdi2290): defer complete if array buffer until done
            responseObserver.complete();
            return;
        }

下面是我在cmd中得到的代码：

​

C:\Users\xx-nj\Desktop\DukhanApp\DukhanColor>ionic serve
Starting app-scripts server: --address 0.0.0.0 --port 8100 --livereload-port 35729 --dev-logger-port 53703 --nobrowser -
Ctrl+C to cancel
[20:02:52]  watch started ...
[20:02:52]  build dev started ...
[20:02:53]  clean started ...
[20:02:53]  clean finished in 3 ms
[20:02:53]  copy started ...
[20:02:53]  deeplinks started ...
[20:02:53]  deeplinks finished in 573 ms
[20:02:53]  transpile started ...
[20:03:01]  transpile finished in 7.70 s
[20:03:01]  preprocess started ...
[20:03:01]  preprocess finished in 1 ms
[20:03:01]  webpack started ...
[20:03:01]  copy finished in 8.80 s
[20:03:09]  webpack finished in 8.01 s
[20:03:09]  sass started ...
Without `from` option PostCSS could generate wrong source map and will not find Browserslist config. Set it to CSS file path or to `undefined` to prevent this warning.
[20:03:13]  sass finished in 3.39 s
[20:03:13]  postprocess started ...
[20:03:13]  postprocess finished in 14 ms
[20:03:13]  lint started ...
[20:03:13]  build dev finished in 20.14 s
[20:03:13]  watch ready in 20.44 s
[20:03:13]  dev server running: http://localhost:8100/

[OK] Development server running!
     Local: http://localhost:8100
     External: http://192.168.8.111:8100
     DevApp: celltore_ionic3@8100 on NajmLaptop

[20:03:23]  tslint: C:/Users/xx-nj/Desktop/DukhanApp/DukhanColor/src/pages/contactus/contactus.ts, line: 124
            'marker' is declared but never used.

     L123:  let map = new google.maps.Map(element, mapOptions);
     L124:  let marker = new google.maps.Marker({
     L125:    title: this.textStatic['cellstore_contact_us_title'],

[20:03:23]  tslint: ...s/xx-nj/Desktop/DukhanApp/DukhanColor/src/pages/detailcategory/detailcategory.ts, line: 138
            Duplicate variable: 'filter'

     L138:  for (var filter in this.filter['valueCustom']) {
     L139:      let attr = this.filter['value'][filter];

[20:03:23]  tslint: ...s/xx-nj/Desktop/DukhanApp/DukhanColor/src/pages/detailcategory/detailcategory.ts, line: 140
            Duplicate variable: 'option'

     L139:  let attr = this.filter['value'][filter];
     L140:  if (attr && Object.keys(attr).length > 0) for (var option in attr) {
     L141:                  if(option != 'select' && attr[option]) {

[20:03:23]  tslint: C:/Users/xx-nj/Desktop/DukhanApp/DukhanColor/src/pages/brand/brand.ts, line: 121
            Duplicate variable: 'filter'

     L121:  for (var filter in this.filter['valueCustom']) {
     L122:      let attr = this.filter['value'][filter];

[20:03:23]  tslint: C:/Users/xx-nj/Desktop/DukhanApp/DukhanColor/src/pages/brand/brand.ts, line: 123
            Duplicate variable: 'option'

     L122:  let attr = this.filter['value'][filter];
     L123:  if (attr && Object.keys(attr).length > 0) for (var option in attr) {
     L124:      if(option != 'select' && attr[option]) {

[20:03:23]  tslint: C:/Users/xx-nj/Desktop/DukhanApp/DukhanColor/src/pages/home/home.ts, line: 300
            Duplicate variable: 'diff'

     L299:  element[i]["due_date"] = false;
     L300:  var diff = (start.getTime() - today.getTime()) / 1000;
     L301:  element[i]['time_diff'] = Math.floor(diff);

[20:03:23]  tslint: C:/Users/xx-nj/Desktop/DukhanApp/DukhanColor/src/pages/home/home.ts, line: 165
            'remaining_time' is declared but never used.

     L164:  ngOnInit() {
     L165:      var remaining_time = setInterval(() => {
     L166:          if (this.navCtrl.getActive().component.name == "HomePage") {

[20:03:23]  tslint: C:/Users/xx-nj/Desktop/DukhanApp/DukhanColor/src/pages/search/search.ts, line: 213
            Duplicate variable: 'filter'

     L213:  for (var filter in this.filter['valueCustom']) {
     L214:      let attr = this.filter['value'][filter];

[20:03:23]  tslint: C:/Users/xx-nj/Desktop/DukhanApp/DukhanColor/src/pages/search/search.ts, line: 215
            Duplicate variable: 'option'

     L214:  let attr = this.filter['value'][filter];
     L215:  if (attr && Object.keys(attr).length > 0) for (var option in attr) {
     L216:      if(option != 'select' && attr[option]) {

[20:03:23]  lint finished in 10.05 s

​

Answer 1

似乎平台没有正确返回，这就是它为空的原因。

您没有包含您的构造函数，所以我不知道您的构造函数是什么样子的，但是下面的代码片段使用您在代码中使用的Device plugin正确地返回了平台名称。

import { Device } from '@ionic-native/device';

constructor(private device: Device) {}

......

if(this.device.platform.toLowerCase()=='android'){
    // Your logic here
}

Answer 2

发生这种情况是因为你在web上运行ionic serve，而cordova平台在那里不可用。当试图从{}对象中检索数据时，它将返回null。

请尝试添加以下代码：

import { Platform } from 'ionic-angular';

//add it in constructor as follows:
constructor( public platform: Platform){

}
//add platform check
if (this.platform.is('cordova')) {
   //add your code here
}else{
   console.log("Plugin not supported on web");
}