Regex provides much more flexibility.
//document.location.href = "http://aaa.bbb.ccc.com/asdf/asdf/sadf.aspx?blah
//1.
var r = new RegExp(/http:\/\/[^/]+/);
var match = r.exec(document.location.href) //gives http://aaa.bbb.ccc.com
//2.
var r = new RegExp(/http:\/\/[^/]+\/[^/]+/);
var match = r.exec(document.location.href) //gives http://aaa.bbb.ccc.com/asdf