javascript去檢測(類似ping)區網有無這個ip

http://stackoverflow.com/questions/4282151/is-it-possible-to-ping-a-server-from-javascript
修改後：

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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);    }     };   this.start = new Date().getTime();   this.img.src = "http://" + ip;   this.timer = setTimeout(function() {    if (_that.inUse) {     _that.inUse = false;     _that.callback('timeout');    }   }, 1500);  } };   //使用： new ping('192.168.0.88', function(status, e) {  console.log(status); });

有這個ip，在控制台會顯示 responded，沒有則會顯示timeout