What is pushState for?

I saw the latest backbone.js (0.5) introduced the pushState option for r开发者_C百科outing.

After reading through https://developer.mozilla.org/en/dom/manipulating_the_browser_history I have to say it is not very clear to me : what pushState is and what exactly it is that pushState brings, in the context of writing a web app with backbone; is it for :

• improving urls: to have a 'real', bookmarkable, 'server-reachable' url, as opposed to hashes?

• graceful degradation: allow the server to render correct pages without JS enabled ?

• both/none of the above, or other reasons ?

Also, what am i doing wrong below ?:

class MyRouter extends Backbone.Router
  routes :
    ''       : 'index'
    '#hello' :'hello'

  index : -> console.log 'index'
  hello: -> console.log 'hello'

new MyRouter

Backbone.history.start pushState: true

When I navigate to http://localhost#hello, the url is changed to http://localhost/#hello, but the callback is not fired ?

Thanks

---

You don't need the # prefix in your routes table. Try this:

  routes :
    ''       : 'index'
    'hello'  : 'hello'

As for pushState I think its both of the above. It does mean more work on the server-side than you would have to do with location hash because you are going to have to make sure that your server can serve pages for all those URLs.