获取浏览器的ip地址

<script src="http://pv.sohu.com/cityjson?ie=utf-8"></script>
<script type="text/javascript">

alert(returnCitySN["cip"] + ',' + returnCitySN["cname"]);
alert(navigator.userAgent);
alert(navigator.platform);
alert(navigator.appName);

</script>