function isEmpty(val){
    return (val === undefined || val == null || val.length <= 0) ? true : false;
}

let empids = new Array();
db.questionaries.find().forEach(function(u) {
    db.employees.find({"userid":u.userid}).forEach(e => {
        if(isEmpty(e.inn) && !isEmpty(u.inn)) {
            empids.push(e.employeeid);
            db.employees.updateOne({"userid":u.userid}, {$set:{"inn":u.inn}});
        };
    });
});