javascript IP地址问题，如果无法加载/没有互联网连接怎么办？

I have some code that if I'm at home; it will display at popup saying that if you are at home. If you are not at home it will display a popup saying you are not at home. As the script is located on a server to give an IP address, how can I get it to say if you are not connected to the internet, as it will fail to load so I would have though that ip!="" would work but doesn't what have I done wrong? ThanksI have some code that if I'm at home; it will d