调试易

js如何实现自动更换播放地址
var url="2011.mp3"
var path=new Array("http://111.xxx.com/","http://222.xxx.com/","http://333.xxx.com/","http://444.xxx.com/");怎样实现wmp 播放不了http://www.xxx.com/2011.mp3 的时候 自动一个个尝试下面的链接
http://111.xxx.com/2011.mp3，
http://222.xxx.com/2011.mp3，
http://333.xxx.com/2011.mp3，
http://444.xxx.com/2011.mp3如果试到http://222.xxx.com/2011.mp3有效就停止，若无效则继续试下去，直到试完。若全部都没用就alert提示。。