stored_javascript.js

> db.system.js.save({_id: "sum", value: function(x,y){return x+y;}})
> db.eval("sum(2,3);")
5
> db.numbers.save({x:4,y:2});
> db.numbers.save({x:4,y:3});
> db.numbers.save({x:3,y:3});
> db.numbers.find({$where: "sum(this.x, this.y)==6"})
{ "_id" : ObjectId("4e91283ecf719df59d2da787"), "x" : 4, "y" : 2 }
{ "_id" : ObjectId("4e91284acf719df59d2da789"), "x" : 3, "y" : 3 }