Javascript 修改 URL 参数

String.prototype.changeQuery = function(name,value)
{
var reg = new RegExp("(^|)"+ name +"=([^&]*)(|$)");
var tmp = name + "=" + value;
if(this.match(reg) != null)
{
return this.replace(eval(reg),tmp);
}
else
{
if(this.match("[\?]"))
{
return this + "&" + tmp;
}
else
{
return this + "?" + tmp;
}
}
}
var href = 'http://dlib.apabi.com/?Token=44AB&cult=CN&orgid=pku';

alert("old url is -- "+href);
href = href.changeQuery("cult","US");
alert("new url is -- "+href);