Database records:
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~
> db.cars.find()
{ "_id" : 100, "available" : 1, "color" : "red", "name" : "GTO", "year" : 3939 }

Below commands works as expected:
> db.cars.find( {available : 1, year : 3939})
{ "_id" : 100, "available" : 1, "color" : "red", "name" : "GTO", "year" : 3939 }

>
> db.cars.find( { $where: "this.available == 1" && "this.year == 3939" })
{ "_id" : 100, "available" : 1, "color" : "red", "name" : "GTO", "year" : 3939 }

>
>
> db.cars.find( { $where: "this.available == 1" || "this.year == 3939" })
{ "_id" : 100, "available" : 1, "color" : "red", "name" : "GTO", "year" : 3939 }


Problem seen:
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

> ####  The below command uses OR condition operation (i.e using || ) and only one condition is true. But still the entry is not displayed.. This is incorrect.
> db.cars.find( { $where: "this.available == 11" || "this.year == 3939" })

>#### The below command uses AND condition operation (i.e using && ) and only one condition is true, but entry is displayed which is incorrect. For AND condition both the expression should return TRUE.
> db.cars.find( { $where: "this.available == 11" && "this.year == 3939" })
{ "_id" : 100, "available" : 1, "color" : "red", "name" : "GTO", "year" : 3939 }