node_mongo_bulk_find_n_upsert

let bulk = db.collection('myCollection').initializeOrderedBulkOp();

  for(let i=0; i < arr.length; i++){
      bulk.find( {findData: arr[i]} ).upsert().updateOne(
          {
              $set: { modData: 'yolo' }
          }
      );
  }
  
  bulk.execute(function(err){
      db.close();
      if(err){
          // do err
      } else {
          // well done
      }
  });

from my experience sometimes this operation not granted (mongo v3.2)