WhereNull Object
WhereNull is a WhereExpression subclass with just a null in it. This object has no members besides the one exposed by WhereExpression. This is used in where expressions like fieldname is null, the null would be represented by a WhereNull object.
Where expressions are used to filter a request by applying extra conditions. They are generally stored as an XML formatted string; however, the scripting implementation can unwrap these into a tree. The WhereBuilder object can be used to create new instances of these objects.
The code snippet below shows how the WhereNull Object can be created:
var VarNull = WhereBuilder.createNull();