const bdb = require('bdb');
const db = bdb.create('/path/to/my.db');

await db.open();

const myPrefix = bdb.key('r');
const myKey = bdb.key('t', ['hash160', 'uint32']);

const bucket = db.bucket(myPrefix.encode());
const batch = bucket.batch();

const hash = Buffer.alloc(20, 0x11);

// Write `foo` to `rt[1111111111111111111111111111111111111111][00000000]`.
batch.put(myKey.encode(hash, 0), Buffer.from('foo'));

await batch.write();

// Iterate:
// From: `rt[0000000000000000000000000000000000000000][00000000]`
// To: `rt[ffffffffffffffffffffffffffffffffffffffff][ffffffff]`
const iter = bucket.iterator({
  gte: myKey.min(),
  lte: myKey.max(),
  values: true
});

await iter.each((key, value) => {
  // Parse each key.
  const [hash, index] = myKey.decode(key);
  console.log('Hash: %s', hash);
  console.log('Index: %d', index);
  console.log('Value: %s', value.toString());
});

// Async Iterator is same, just used with for await syntax.:
// From: `rt[0000000000000000000000000000000000000000][00000000]`
// To: `rt[ffffffffffffffffffffffffffffffffffffffff][ffffffff]`
const asyncIter = bucket.iterator({
  gte: myKey.min(),
  lte: myKey.max(),
  values: true
});

for await (const {key, value} of asyncIter) {
  const [hash, index] = myKey.decode(key);
  console.log('Hash: %s', hash.toString('hex'));
  console.log('Index: %d', index);
  console.log('Value: %s', value.toString());
}

await db.close();