DOM domain

//获得url
var url = document.URL;
//获得域名
var domain = document.domain;

//取得源页面的url
var referrer = document.referrer;

1. 对domian赋值不能跨域

比如在show.17173.com;

document.domain = 17173.com; //success

doucment.domain = baidu.com;// fail

2. 只能向下赋值

比如在show.17173.com;

document.domain = 17173.com; //success

document.domani = show.17173.com // fail