JavaScript YUI read code Diary of the Yahoo.util.dom-part.4_yui. Ext Related

var getxy = function () {
To determine if it is IE
if (document.documentElement.getBoundingClientRect) {
Note 1
return function (EL) {
var box = El.getboundingclientrect ();

var rootnode = el.ownerdocument;
return [Box.left +
Y.dom.getdocumentscrollleft (RootNode), Box.top +
Y.dom.getdocumentscrolltop (RootNode)];
};
} else {
return function (EL) {
var pos = [El.offsetleft, el.offsettop];
var parentnode = el.offsetparent;

To determine if the node is absolute under Safari,
and whether the parent element is body
Note 2.
var accountforbody = (Issafari &&
Y.dom.getstyle (el, ' position ') = = ' absolute ' &&
El.offsetparent = = El.ownerDocument.body);

If the parent element is not itself
if (parentnode!= el) {
while (parentnode) {
Pos[0] + = Parentnode.offsetleft;
POS[1] + = Parentnode.offsettop;
if (!accountforbody && Issafari &&
Y.dom.getstyle (parentnode, ' position ')
= = ' absolute ') {
Accountforbody = true;
}
ParentNode = parentnode.offsetparent;
}
}

It's for Safari.
if (accountforbody) {//safari Doubles in the This case
Pos[0]-= el.ownerDocument.body.offsetLeft;
POS[1]-= EL.OWNERDOCUMENT.BODY.OFFSETTOP;
}
ParentNode = El.parentnode;

Account for any scrolled ancestors
while (Parentnode.tagname &&
!patterns. Root_tag.test (Parentnode.tagname))
{
Work around opera inline/table Scrollleft/top bug
Note 3.
if (Y.dom.getstyle (parentnode, ' Display ')
. Search (/^inline|table-row.*$/i)) {
Pos[0]-= parentnode.scrollleft;
POS[1]-= parentnode.scrolltop;
}

ParentNode = Parentnode.parentnode;
}

return POS;
};
}
} ()//note:executing for loadtime branching note. The Getboundingclientrect method about IE can refer to here.
Note. Safari BUG, see here for details.
Note: Refer to the Foreigner's exact words (provenance).
"-Remove parent scroll unless that parent is inline or a table
To work around Opera inline/table scrollleft/top bug "
Fixed in Opera 9.5. (Also, Opera 9.5 supports Getboundingclientrect
and getclientrects.) Finally, for more DOM compatibility, see PPK's summary (how is he again).