Datastore items sort incorrectly on attributes with null values

[gizmojo.org]

Datastore items sort incorrectly on a attribute/column for which some items have the attribute set to null.

The datastore ReadAPI doc for the "sort" parameter states:

when comparing attributes, if an item contains no value for the attribute (undefined), then it the default ascending sort logic should push it to the bottom of the list. In the descending order case, it such items should appear at the top of the list.

One would expect this same behaviour for attributes that are set to the javascript null (that is generally more or less used in equivalent way to javascript undefined).

To reproduce [working with revision 10544] take the test file at: dojox/data/demos/demo_DataDemoTable.html and modify the countries.json file that is loaded into the first datastore, by adding a:

    population:null

attribute to a bunch of country items that do not have it. Then reload, and try sorting on the population column.

[Jared Jurkiewicz]

Actually, null is an object. It's not 'undefined'. Has an actual different meaning. Fixing should be easy, though, to make it act similar.

[Jared Jurkiewicz]

(In [10710]) Minor fix to sorter. fixes #4491

[Jared Jurkiewicz]

Tested on Firefox, Safari B3, and IE 6