类型错误“未定义”不是对象(计算“navigator.connection.type”)

Question

我正在构建一个Cordova应用程序，其中我正在使用Cordova网络信息插件org.apache.cordova.network-information。在过去的几天里，我在safari中调试web-inspector时发现了这个奇怪的bug，里面写着“类型错误‘未定义’不是一个对象(计算'navigator.connection.type')”。在初始加载期间，它工作得很好，但在应用程序中进一步导航时，会显示此错误，并且应用程序冻结。在iOS 8中，它经常出现，但在安卓棒棒糖中，它偶尔会出现。我已经尝试了所有关于这方面的建议或帖子，但都无济于事。我使用的是科尔多瓦4.3版，iOS 8.1。非常感谢任何人的帮助，很抱歉不能发布任何关于这方面的图片，因为我没有足够的声誉来发布它

    function checkConnection() { 
    alert(navigator.connection.type);
    var networkState = navigator.connection.type;

   var states = {};
    states[Connection.UNKNOWN]  = 'Unknown connection';
    states[Connection.ETHERNET] = 'Ethernet connection';
    states[Connection.WIFI]     = 'WiFi connection';
    states[Connection.CELL_2G]  = 'Cell 2G connection';
    states[Connection.CELL_3G]  = 'Cell 3G connection';
    states[Connection.CELL_4G]  = 'Cell 4G connection';
    states[Connection.CELL]     = 'Cell generic connection';
    states[Connection.NONE]     = 'No network connection';
    if(networkState == Connection.UNKNOWN || networkState == Connection.NONE){
        navigator.notification.alert('No Network Available',null,"Warning");
        sessionStorage.setItem('UserID',"");
        $.mobile.changePage("#loginPage", {
                            transition: 'none',
                            showLoadMsg: true
                            });
        return false;
    }else{
        return true;
   }
}

Answer 1

在我的例子中，问题是我在device ready之外调用函数，所以这样做解决了我的问题：

document.addEventListener("deviceready", function(){
     // do your  navigator.connection.type stuff here 
    }, false);

Answer 2

请检查您是否已声明这些内容

<feature name="NetworkStatus">
         <param name="android-package" value="CDVConnection" />
 </feature>

网络状态将是功能名称，值将是您的类名。

在Android Manifest中，

 <uses-permission android:name="android.permission.READ_PHONE_STATE"/>

Aso检查cordova_plugin.js

cordova.define('cordova/plugin_list', function(require, exports, module) {
    module.exports = [{
        "file": "plugins/org.apache.cordova.dialogs/www/notification.js",
        "id": "org.apache.cordova.dialogs.notification",
        "merges": ["navigator.notification"]
    }, {
        "file": "plugins/org.apache.cordova.network-information/www/network.js",
        "id": "org.apache.cordova.network-information.network",
        "clobbers": ["navigator.connection", "navigator.network.connection"]
    }];
    module.exports.metadata = // TOP OF METADATA 
    {
        "org.apache.cordova.device": "0.2.8",
        "org.apache.cordova.network-information": "0.2.7"
    }
});

Answer 3

我使用cordova-plugin-network-information也遇到了同样的问题。我注意到的是，尽管在"deviceready“被触发后被调用，navigator.connection.type对象仍然是未定义的。我的解决方法是将调用延迟200ms，之后对象就可以使用了。

function checkConnection(){
    try{
        console.log(navigator.connection.type);
    }
    catch(e){
        alert("error : "+e);
    }

    setTimeout(function(){
        var networkState = navigator.connection.type;
        console.log(networkState);

        var states = {};
        states[Connection.UNKNOWN]  = 'Unknown connection';
        states[Connection.ETHERNET] = 'Ethernet connection';
        states[Connection.WIFI]     = 'WiFi connection';
        states[Connection.CELL_2G]  = 'Cell 2G connection';
        states[Connection.CELL_3G]  = 'Cell 3G connection';
        states[Connection.CELL_4G]  = 'Cell 4G connection';
        states[Connection.CELL]     = 'Cell generic connection';
        states[Connection.NONE]     = 'No network connection';

//        alert('Connection type: ' + states[networkState]);
        if(states[networkState] == "No network connection"){
            window.location.assign("lostConnection.html");
        }
    }, 200);
}

因此，"try/catch“序列将会因为一个未定义的对象而失败，但是200ms之后，对navigator.connection.type的调用就成功了，这对我来说是件好事！