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我要做的是检查互联网连接，如果无法连接，它会再试几次。我目前用来检查的代码位于https://gist.github.com/fryn/943537，因为它似乎是最有希望的（我对其他解决方案的运气不太好）。

我的问题是“serverReachable()”函数似乎总是返回 false，即使连接了互联网。有什么建议么？我愿意使用其他解决方案，这只是我迄今为止得到的最接近的解决方案。

谢谢！

这是我的代码：（所有警报都用于调试目的）

var attemptCount = 0;

    function onOffLine(){
      alert("start of onOffLine function");
      var z = "N";
      var connectionTest = serverReachable();
      if(serverReachable()){
        alert("found to have connection.");
        document.getElementById("connected").style.visibility = "visible";
        document.getElementById("notConnected").style.visibility = "hidden";
        z = "yes";
        alertMe(z);
      }else if(connectionTest == false && attemptCount < 4){
        document.getElementById("notConnected").style.visibility = "visible";
        alert("No connection, recursing.." + attemptCount);
        attemptCount++;
        setTimeout("onOffLine()", 3000);
      }else if(attemptCount == 4){
        alert("all attempts failed.");
        document.getElementById("notConnected").style.visibility = "visible";
        z = "N";
        alertMe(z);
      }
    }

    function alertMe(z){
      if(z == "N"){
        alert("Browser is loaded;\nInternet not connected");
      }else if(z == "Y"){
        alert("Browser is open and ready");
      }
    }

    function serverReachable() {
      alert("serverReachable() called");
      var x = new XMLHttpRequest;
      x.open('HEAD', '/?' + +new Date, false);
      try {
        x.send();
        var s = x.status;
        return s >= 200 && s < 300 || s === 304;
      } catch (e) {
        return false;
      }
    }
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