pushstate and seo

No, the talk about pushState is geared around accomplishing the same general process to hashbangs, but with better-looking URLs. Think about what really happens when you use hashbangs...

You say:

With hashbangs, google knows to go to the escaped_fragment url to get their static content.

So in other words,

As you can see, it already relies on the server. If you aren't serving a snapshot of the content from the server, then your site isn't getting indexed properly.

With pushState, google just sees nothing as it can't use the javascript to load the json and subsequently create the template.

Actually, Google will see whatever it can request at site.com/blog. A URL still points to a resource on the server, and clients still obey this contract. Of course, for modern clients, Javascript has opened up new possibilities for retrieving and interacting with content without a page refresh, but the contracts are the same.

So the intended elegance of pushState is that it serves the same content to all users, old and new, JS-capable and not, but the new users get an enhanced experience.

The Facebook approach — serve the same content at the URL site.com/blog that your client app would transform into when you push /blog onto the state. (Facebook doesn't use pushState yet that I know of, but they do this with hashbangs)

The Twitter approach — redirect all incoming URLs to the hashbang equivalent. In other words, a link to "/blog" pushes /blog onto the state. But if it's requested directly, the browser ends up at #!/blog. (For Googlebot, this would then route to _escaped_fragment_ as you want. For other clients, you could pushState back to the pretty URL).

In a couple different comments, you said

escaped fragment is completely different. You can serve pure unthemed content, cached content, and not be put under the load that normal pages are.

The ideal solution is for google to either do javascript sites or implement some way of knowing that there's an escaped fragment url even for pushstate sites (robots.txt?).

The benefits you mentioned are not isolated to _escaped_fragment_. That it does the rewriting for you and uses a specially-named GET param is really an implementation detail. There is nothing really special about it that you couldn't do with standard URLs — in other words, rewrite /blog to /?content=/blog on your own using mod_rewrite or your server's equivalent.

If you can't rewrite URLs and serve some kind of content at /blog (or whatever state you pushed into the browser), then your server is really no longer abiding by the HTTP contract.

This is important because a page reload (for whatever reason) will pull content at this URL. (See https://wiki.mozilla.org/Firefox_3.6/PushState_Security_Review — "view-source and reload will both fetch the content at the new URI if one was pushed.")

It's not that drawing user interfaces once on the client-side and loading content via JS APIs is a bad goal, its just that it isn't really accounted for with HTTP and URLs and it's basically not backward-compatible.

At the moment, this is the exact thing that hashbangs are intended for — to represent distinct page states that are navigated on the client and not on the server. A reload, for example, will load the same resource which can then read, parse, and process the hashed value.

It just happens to be that they have also been used (notably by Facebook and Twitter) to change the history to a server-side location without a page refresh. It is in those use cases that people are recommending abandoning hashbangs for pushState.

If you render all content client-side, you should think of pushState as part of a more convenient history API, and not a way out of using hashbangs.