On 1/21/10 11:12 AM, Darin Fisher wrote:
In WebKit, history.back() is currently implemented asynchronously.
However, it was not always this way. Previously, if the back navigation
corresponded to a hash change, then the back navigation would complete
synchronously. If the back navigation corresponded to a different
document, then it would be completed asynchronously.
The HTML5 spec currently calls for the old behavior of WebKit, which
happens to match the behavior of Gecko. Because the spec is written
this way, there is movement in WebKit to change WebKit back.
IE however appears to implement history.back() asynchronously in all
cases just like newer versions of WebKit.
I actually think this is a better behavior to spec for a couple reasons:
1) It allows for history.back() to behave consistently regardless of
the type of navigation.
2) It allows for the back/forward list to be decoupled from the main
thread of the rendering engine.
This last point is quite relevant to Chrome since we store the
back/forward list in a separate process. We do this since items in the
back/forward list may actually need to be rendered using different
WebKit processes. (Navigating in the location bar is a hint that we can
spawn a new process.)
We could copy the entire back/forward list to each process and replicate
state, but that seems excessive. Instead, simply matching the
history.back() behavior of IE avoids the need to do so.
From a web compat perspective, it seems wise to match the behavior of
IE. It also has other benefits.
Can we change the spec?
-Darin
Do you propose to make all history traversal async?
back/forward/go/location.reload ?
-Olli
