How could I change window's location without reloading and # hack?

At first I thought that hash hack is a requirement, however judging from the recent updates from facebook, I am thinking otherwise.

The original hash hack (I am not sure if this is the correct term) is that by changing location.hash, one may save a state in the URL without refreshing the page. That is extensively used by Google's apps, and Facebook, and lately #NewTwitter. However today I noticed that Facebook no longer have this "#" if you use a "modern" browser - like chrome or firefox. I double checked that they are not reloading by using developer tools and firebug respectively.

With a minimal search in stackoverflow, the closest one to the solution is using Flash - however I disabled Flash and facebook.com still works like a charm. Judging from the coverage in chrome 8 dev and开发者_开发技巧 firefox 4 beta, I wonder that could be related to HTML5-era APIs, but the code in Facebook is not of my capacity to debug to find out what they did.

Since this is like the first question I ask here, I wonder if any of you may have already solved this problem.

Thanks guys.

P.S. Doesn't work on IE8, haven't tested on IE9 beta.

Facebook is using the history api in HTML5. From this blog post you can see how this works. Basically they are making calls like the one below to change the url without reloading the page.

window.history.pushState("object or string", "Title", "/new-url");

Here is the HTML5 working draft spec about it: http://www.whatwg.org/specs/web-apps/current-work/multipage/history.html#the-location-interface

Sadly, IE9 does not support this api. New versions of Chrome and FF have full support.