I modified a JSFiddle from rniemeyer to illustrate the problem: http://jsfiddle.net/mTqMt/1/
<div class="container" data-bind="sortable: groupOrItems">
<!--ko if: type=='Group'-->
<div>
<div class="title" data-bind="text: name()"></div>
<!--here I would actually have a nested sortable-->
</div>
<!--/ko-->
<!--ko if: type=='Item'-->
<div class="item" data-bind="text: name()"></div>
<!--/ko-->
</div>
Firebug says: "TypeError: node is null" line 546 in knockout-latest.debug.js
I tried it with "foreach" instead of "sortable" and then it worked.
Any ideas?
The sortable binding and jQuery UI sortable really needs a parent element to grab onto for the stuff that you are sorting.
You would want to at least wrap your whole "item" in an element like:
Updated: http://jsfiddle.net/rniemeyer/FSYYb/