navigator.onLine并不总是有效 [英] navigator.onLine not always working

问题描述

我遇到了navigator.onLine属性的问题。

I'm having an issue with the navigator.onLine property.

我正在运行WAMP的本地信息亭运行一个简单的网站。

I'm running a simple website from a local kiosk running on a WAMP.

在我的笔记本电脑上进行测试时，它可以正常工作。我关闭WiFi并显示警告框。在运行WAMP软件的自助服务终端上断开互联网连接不会产生错误状态。有什么想法吗？

On my laptop when I test this it works. I turn off WiFi and the alert box shows up. Disconnecting the internet on the kiosk running the WAMP software does not produce the false status. Any ideas why?

var online = navigator.onLine;

if (online == false) {

    alert("Sorry, we currently do not have Internet access.");
    location.reload();

}

推荐答案

MDN关于 navigator.onLine ：

在Chrome和Safari中，如果浏览器无法连接到局域网（LAN）或路由器，则它处于脱机状态;所有其他条件都返回true。因此，虽然您可以假设浏览器在返回false值时处于脱机状态，但您不能认为真值必然意味着浏览器可以访问互联网。

In Chrome and Safari, if the browser is not able to connect to a local area network (LAN) or a router, it is offline; all other conditions return true. So while you can assume that the browser is offline when it returns a false value, you cannot assume that a true value necessarily means that the browser can access the internet.

如上所述，此属性不可信，因此，在我看来，最佳解决方法是对服务器端页面的ajax调用。如果浏览器处于脱机状态，则连接将失败，因此将调用 onerror 事件。否则，将调用 onload 事件：

As described above, this property is not trustable, so, in my opinion, the best workaround is an ajax call to a server-side page. If the browser is offline, then the connection will fail and, thus, the onerror event will be called. Otherwise, the onload event is called:

function isOnline(no,yes){
    var xhr = XMLHttpRequest ? new XMLHttpRequest() : new ActiveXObject('Microsoft.XMLHttp');
    xhr.onload = function(){
        if(yes instanceof Function){
            yes();
        }
    }
    xhr.onerror = function(){
        if(no instanceof Function){
            no();
        }
    }
    xhr.open("GET","anypage.php",true);
    xhr.send();
}

isOnline(
    function(){
        alert("Sorry, we currently do not have Internet access.");
    },
    function(){
        alert("Succesfully connected!");
    }
);

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