ajax论坛上的无状态（pushState？）后退按钮

I need a stateless way to implement the back button feature in an ajax forum such that if a user is on page 2 of the topics ajax page, and then clicks on the message - when the user then hits the back button they can go back to the point of the message on the topics ajax page. - your help would be much appreciated.I need a stateless way to implement the back bu