JS-ELEMENT-COUNT
The Char and Obj objects both have a count() method on them which returns a count of the number of instances of a vnum are loaded on the mud at any one time.
Char.count( <vnum> ) Obj.count( <vnum> [, 'saved' ] )
For example,
var c = Obj.count( 10000 );
The Obj.count() method also takes an optional 'saved' option that when specified expands the count to include items located in character rent files which are not currently online.