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[whatwg] AJAX History Concerns

From: Brady Eidson <beidson@apple.com>
Date: Wed, 11 Nov 2009 17:48:34 -0800
Message-ID: <EB911329-E0CD-4F0D-8603-4B4D3B976995@apple.com>
For reference see section 6.10.2 of the spec.

In getting an implementation for pushState(), replaceState(), and clearState() going I've had a few concerns.

pushState() and replaceState():

When pushState() or replaceState() are called with a URL argument, the document's current address is changed.  This has a lot of side effects in that it is exposed to scripts and the DOM and most modern user agents would update their UI to show this.

However, this same section takes care to point out "The title is purely advisory. User agents might use the title in the user interface."  Indeed, many user agents would show the title of the current page at the top of the browser window or tab, in their back/forward list, and possibly in their global persistent history.

But unlike the URL which actually changes in the Document object and is therefore exposed to the DOM, this "purely advisory" title change is hidden from the DOM.  I'm questioning the reasoning behind this distinction and am curious if it was intentional or not.

clearState():

The following text describes clearState():

"When this method is invoked, the user agent must remove from the session history all the entries from the first state object entry for that Document object up to the last entry that references that same Document object, if any.

Then, if the current entry was removed in the previous step, the current entry must be set to the last entry for that Document object in the session history."

Imagine the following scenario:

A document has 5 state entries.  
They each have a different URL as follows:  http://www.example.com/page.html?1, http://www.example.com/page.html?2, http://www.example.com/page.html?3, http://www.example.com/page.html?4, and http://www.example.com/page.html?5
The current entry is the 3rd entry.
A script calls "clearState()" so these entries are all cleared out, including the current entry.
Since the current entry was removed, the current entry after the clearState() call is changed to be the last entry for the Document.

My reading of the spec is that after clearState() returns, the entries 1-4 will be gone completely, the state object for entry 5 will have been cleared, and entry 5 will now be the current entry.

This has the side effect of the URL for the current entry - http://www.example.com/page.html?5 - not matching the current URL of the document - http://www.example.com/page.html?3

Is my understanding of what the current entry should be correct?
If not, what am I missing?
And is the disjoint between the Document's URL and the current entries URL correct?
If not, what am I missing?

Thanks,
~Brady
Received on Wednesday, 11 November 2009 17:48:34 UTC

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