Ping with javascript and read errors

I basically follow the accepted answer to this question ( Is it possible to execute a ping server with Javascript? )

Update

It seems to work as expected when a domain lasts 15 characters (actually, http: // + 15, but 16 or more makes it bomb. For more details see below.

The problem that I see is that if you use something similar to a valid domain, for example http://thisisdefinitelynotarealdomainname.com, it returns an error, but the code mentioned considers the errors in order (because most should be). If you look at the error event, I'm not sure I see where I can get the HTTP response code (i.e., if it is 404, consider it invalid).

Here is a jsFiddle showing the problem - they all display "answered". If you look at the console, an invalid domain returns a 404 error, and two valid ones (if the console is chrome, unsure of others) show that they were interpreted as an image, but transmitted as text / html - is there any way to read or a 404 error , or type mime?

var pinger = function () {
    var ping = function (ip, callback) {
        if (!this.inUse) {
            this.status = 'unchecked';
            this.inUse = true;
            this.callback = callback;
            this.ip = ip;
            var _that = this;
            this.img = new Image();
            this.img.onload = function () {
                _that.inUse = false;
                _that.callback('responded');
            };
            this.img.onerror = function (e) {
                if (_that.inUse) {
                    _that.inUse = false;
                    _that.callback('responded', e);
                }
                console.log(e);
            };
            this.start = new Date().getTime();
            this.img.src = "http://" + ip + "/?now=" + this.start; // add the current time to work around caching
            this.time = setTimeout(function () {
                if (_that.inUse) {
                    _that.inUse = false;
                    _that.callback('timeout');
                }
            }, 1500);
        }
    }

    return {
        ping: ping
    };
}();

(function () {
    var output = document.getElementById('output');
    var servers = [
        'localhost',
        'google.com',
        'okthisreallydoesntmakeanysense',
        'okthisreallydoe',
        'thisisashortone',
        'thisisabitlonger'
    ];

    servers.forEach(function (server) {
        new pinger.ping(server, function (status, e) {
            output.innerHTML += server + ': ' + status + '<br />';
        });
    });
})();    

Update

What is even stranger is that it looks up to 15 characters. I updated jsFiddle . See below for those who respond, as I expect, against those who do not. What can cause this?

        'localhost',
        'google.com',
        'okthisreallydoesntmakeanysense', // doesn't work
        'okthisreallydoe', // works (15 characters)
        'thisisashortone', // works (15 characters)
        'thisisabitlonger' // doesn't work (16 characters)