Subj : Re: Sharing Javascript objects between different XUL windows.
To   : Peter Wilson
From : Brendan Eich
Date : Thu Dec 30 2004 01:07 pm

Peter Wilson wrote:
> Somehow we have two different instances of the same DOM Element (see 
> below).
> I tried QueryInterface to nsISupports: they are different objects.
> 
> Interestingly, as well as the same siblings, parent etc. the two objects 
> share the same attributes. I can set an attribute on one and read it 
> back by the other.


Very odd.  Taking this to m.dom for now, cc'ing likely helpers.


> This happens even though I am not mutating the DOM in question. Could GC 
> be causing this problem. The DOM is shared between different forms.
> I am also experiencing occaisional crashes.
> 
> Is there any way to turn off GC from the Firefox command line to see if 
> this eliminates the problem?


No, but first let's verify that GC is happening in a way that could 
cause the problem.  Can you run a debug build?


> 
> 0001: theTreeSrcNode === srcNode
> $[2] = [boolean] false
> 0001: theTreeSrcNode.previousSibling === srcNode.previousSibling
> $[3] = [boolean] true
> 0001: srcNode.id
> $[6] = [string] "content-1"
> 0001: theTreeSrcNode.id
> $[7] = [string] "content-1"
> 0001: theTreeSrcNode == srcNode
> $[8] = [boolean] false
> 0001: theTreeSrcNode.QueryInterface(Components.interfaces.nsISupports)
> $[9] = [XULElement] [class: XULElement] {0}
> 0001: srcNode.QueryInterface(Components.interfaces.nsISupports)
> $[10] = [XULElement] [class: XULElement] {0}
> 0001: srcNode.QueryInterface(Components.interfaces.nsISupports) == 
> theTreeSrcNode.QueryInterface(Components.interfaces.nsISupports)
> $[11] = [boolean] false
> 0001: theTreeSrcNode.setAttribute("TEST","TESTVal")
> $[12] = [void] void
> 0001: theTreeSrcNode.getAttribute("TEST")
> $[13] = [string] "TESTVal"
> 0001: srcNode.getAttribute("TEST")
> $[14] = [string] "TESTVal"

.