A NodeJS script to delete 'orphan' chunks in MongoDB/GridFS database

deleteGridFSChunks.js

//How to run:
//   node deleteGridFSChunks.js <hostname> <databaseName>
const { MongoClient } = require('mongodb');
const args = process.argv.slice(2);

async function main() {
    if (args.length != 2)
    { 
        console.info("Warning\nTwo arguments are required: Hostname and database name");
        return;
    }

    const hostname = args[0];
    const database = args[1];
    
    const client = await MongoClient.connect(`mongodb://${hostname}:27017/`, { useNewUrlParser: true });
    const db = client.db(database);

    const serverStatus = await db.command({ "serverStatus": 1 });
    console.log(`MongoDB server (${hostname}): ${serverStatus.version}`);

    const chunks = db.collection('fs.chunks');
    const cursor = await chunks.aggregate([
        {
            $group: { _id: "$files_id" }
        },
        {
            $lookup: {
                from: "fs.files",
                localField: "_id",
                foreignField: "_id",
                as: "fileList"
            }
        }, 
        {
            $match: { 
                "fileList": { $size: 0 }
            }
        }
    ]);

    let fileIds = await cursor.map(chunk => chunk._id).toArray();
    
    let res = await chunks.deleteMany({ "files_id" : { "$in": fileIds } });
    if (res.result.ok)
        console.log("Deleted Count: " + res.deletedCount);
    else 
        console.error("Unable to delete");
    
    client.close();
}

main().catch(error => console.error(error.stack));