stocks:

{"_id" : ObjectId("xxx"),"scrip" : "xxxxx2" }
{"_id" : ObjectId("xxy"),"scrip" : "xxxxx3" }
{"_id" : ObjectId("xyy"),"scrip" : "..." }

[xxxxx7,xxxxx8]

db.stocks.find({
    "scripid": {"$nin": ["xxxxx7","xxxxx2","xxxxx3","xxxxx8"]}
}).toArray().map(stock => stock.scripid)

{"scripid" : "xxxxx2" }
{"scripid" : "xxxxx3" }
{"scripid" : "xxxxx4" }

db.stocks.aggregate([  {
             $group :{_id : null, scripids: {$push : '$scripid'}}
           },{ "$project": { _id:0 , "inputArrayNINscripts": { "$setDifference": [ ['xxxxx7','xxxxx2','xxxxx3','xxxxx8'] , "$scripids" ] } } } ])

{
    "inputArrayNINscripts" : [
        "xxxxx7",
        "xxxxx8"
    ]
}

db.stocks.find({
    "scripid": {"$nin": ["xxxxx7","xxxxx2","xxxxx3","xxxxx8"]}
}).toArray().map(scriptsNINArray => scriptsNINArray.scripid)

/* 1 */
[
    "xxxxx4"
]