What angularjs expression syntax is this in ng-class

you've probably also seen something like this:

Very rad syntax.

EDIT:
What happens here, is that the "complete" class is added to the element if(item.Id != 0). Alternatively, we could write:

. 1 !== 0 which is "false" -- the "DoubleNegative" class is added to the element.

`

            | |      | |          | | |            |
            | |result| |className | | |            |
            |                     | | |            |
            |       function      | | | condition  |

Addendum

Also, I just realized that you can use a variety of different keys to map to your condition. For example:

ng-class="{ true: 'highlight', undefined: 'mute' }[ item.hasValue ]"

The mute class will be applied if item has no "hasValue" property. Furthermore, you can apply a class for any given type or value:

{'Jonathan Chapman': 'embolden', '[object Object]': 'hide'}[ item.toString() ]

In the following collection, this would embolden a person's name while hiding items that are objects:

[
    'Jonathan Chapman',
    { aka: 'Johnny Applyseed' },
    'Brad Pitt',
    { details: 'Fights Zombies' }
]

With this, you could watch for specific values in any $scope property. I suppose this could come in very handy at times.

Cheers