MongoDB: How to call stored function from nodejs

I'm trying to call stored function from node js using db.eval() and also provided the db connection and it is giving an error - Type Error: db.eval() is not a function.

I'm facing difficulty while calling the stored functions, if anyone know anything it would be helpful,

Thanks i appreciate it.

Here is the function i stored in mongodb.

db.system.js.save({ 
   "_id":"getNumbers",
   "value": function (){
       return db.numbers.find()
    }
})
db.loadServerScripts()

The below snippet that i used for calling stored function, and dbConnection is where i written code for connecting mongo db

const dbConnection =
    require("./dbConnection"); 

function getNum(result) {
     dbConnection.db.eval("getNumbers()", (err, res) => {
           if (err) {
                return result(err);
            } else {
                return result(res);
            }
        }
    }