From aa7f4c28717f17c2825112fced6d628178b975ea Mon Sep 17 00:00:00 2001
From: Robert Nagy <ronagy@icloud.com>
Date: Sun, 7 Mar 2021 21:59:38 +0100
Subject: [PATCH 1/2] fix: update and fix standard

---
 client.js            |  10 +-
 leveldown.js         |  77 ++++++------
 messages.js          | 272 +++++++++++++++++++------------------------
 package.json         |   4 +-
 server.js            |  59 +++++-----
 streams.js           |   6 +-
 test/abstract.js     |  20 ++--
 test/basic.js        |  84 ++++++-------
 test/concurrent.js   |  28 ++---
 test/encryptdown.js  |  30 ++---
 test/retry.js        |  66 +++++------
 test/streams.js      |  28 ++---
 test/subleveldown.js |  68 +++++------
 13 files changed, 362 insertions(+), 390 deletions(-)

diff --git a/client.js b/client.js
index 8db3488..9baadb8 100644
--- a/client.js
+++ b/client.js
@@ -1,12 +1,12 @@
-var levelup = require('levelup')
-var encode = require('encoding-down')
-var leveldown = require('./leveldown')
+const levelup = require('levelup')
+const encode = require('encoding-down')
+const leveldown = require('./leveldown')
 
 module.exports = function (opts) {
   if (!opts) opts = {}
 
-  var down = leveldown(Object.assign({}, opts, { onflush: onflush }))
-  var db = levelup(encode(down, opts), opts)
+  const down = leveldown(Object.assign({}, opts, { onflush: onflush }))
+  const db = levelup(encode(down, opts), opts)
 
   db.createRpcStream = db.connect = connect
   db.isFlushed = isFlushed
diff --git a/leveldown.js b/leveldown.js
index e65ce71..7903a29 100644
--- a/leveldown.js
+++ b/leveldown.js
@@ -1,14 +1,14 @@
-var duplexify = require('duplexify')
-var abstract = require('abstract-leveldown')
-var util = require('util')
-var eos = require('end-of-stream')
-var ids = require('numeric-id-map')
-var lpstream = require('length-prefixed-stream')
-var reachdown = require('reachdown')
-var messages = require('./messages')
-var matchdown = require('./matchdown')
-
-var ENCODERS = [
+const duplexify = require('duplexify')
+const abstract = require('abstract-leveldown')
+const util = require('util')
+const eos = require('end-of-stream')
+const ids = require('numeric-id-map')
+const lpstream = require('length-prefixed-stream')
+const reachdown = require('reachdown')
+const messages = require('./messages')
+const matchdown = require('./matchdown')
+
+const ENCODERS = [
   messages.Get,
   messages.Put,
   messages.Delete,
@@ -16,7 +16,7 @@ var ENCODERS = [
   messages.Iterator
 ]
 
-var DECODERS = [
+const DECODERS = [
   messages.Callback,
   messages.IteratorData
 ]
@@ -47,18 +47,19 @@ Multilevel.prototype.createRpcStream = function (opts, proxy) {
   if (!opts) opts = {}
   this._ref = opts.ref || null
 
-  var self = this
-  var encode = this._encode
-  var decode = lpstream.decode()
+  const self = this
+  const encode = this._encode
+  const decode = lpstream.decode()
 
   decode.on('data', function (data) {
     if (!data.length) return
-    var tag = data[0]
+    const tag = data[0]
     if (tag >= DECODERS.length) return
 
-    var dec = DECODERS[tag]
+    const dec = DECODERS[tag]
+    let res
     try {
-      var res = dec.decode(data, 1)
+      res = dec.decode(data, 1)
     } catch (err) {
       return
     }
@@ -93,14 +94,14 @@ Multilevel.prototype.createRpcStream = function (opts, proxy) {
       return
     }
 
-    for (var i = 0; i < self._requests.length; i++) {
-      var req = self._requests.get(i)
+    for (let i = 0; i < self._requests.length; i++) {
+      const req = self._requests.get(i)
       if (!req) continue
       self._write(req)
     }
 
-    for (var j = 0; j < self._iterators.length; j++) {
-      var ite = self._iterators.get(j)
+    for (let j = 0; j < self._iterators.length; j++) {
+      const ite = self._iterators.get(j)
       if (!ite) continue
       ite.options = ite.iterator._options
       self._write(ite)
@@ -108,14 +109,14 @@ Multilevel.prototype.createRpcStream = function (opts, proxy) {
   }
 
   function oniteratordata (res) {
-    var req = self._iterators.get(res.id)
+    const req = self._iterators.get(res.id)
     if (!req) return
     req.pending.push(res)
     if (req.callback) req.iterator.next(req.callback)
   }
 
   function oncallback (res) {
-    var req = self._requests.remove(res.id)
+    const req = self._requests.remove(res.id)
     if (req) req.callback(decodeError(res.error), decodeValue(res.value, req.valueAsBuffer))
   }
 }
@@ -135,13 +136,13 @@ Multilevel.prototype._flushMaybe = function () {
 }
 
 Multilevel.prototype._clearRequests = function (closing) {
-  for (var i = 0; i < this._requests.length; i++) {
-    var req = this._requests.remove(i)
+  for (let i = 0; i < this._requests.length; i++) {
+    const req = this._requests.remove(i)
     if (req) req.callback(new Error('Connection to leader lost'))
   }
 
-  for (var j = 0; j < this._iterators.length; j++) {
-    var ite = this._iterators.remove(j)
+  for (let j = 0; j < this._iterators.length; j++) {
+    const ite = this._iterators.remove(j)
     if (ite) {
       if (ite.callback && !closing) ite.callback(new Error('Connection to leader lost'))
       ite.iterator.end()
@@ -160,7 +161,7 @@ Multilevel.prototype._serializeValue = function (value) {
 Multilevel.prototype._get = function (key, opts, cb) {
   if (this._db) return this._db._get(key, opts, cb)
 
-  var req = {
+  const req = {
     tag: 0,
     id: 0,
     key: key,
@@ -175,7 +176,7 @@ Multilevel.prototype._get = function (key, opts, cb) {
 Multilevel.prototype._put = function (key, value, opts, cb) {
   if (this._db) return this._db._put(key, value, opts, cb)
 
-  var req = {
+  const req = {
     tag: 1,
     id: 0,
     key: key,
@@ -190,7 +191,7 @@ Multilevel.prototype._put = function (key, value, opts, cb) {
 Multilevel.prototype._del = function (key, opts, cb) {
   if (this._db) return this._db._del(key, opts, cb)
 
-  var req = {
+  const req = {
     tag: 2,
     id: 0,
     key: key,
@@ -204,7 +205,7 @@ Multilevel.prototype._del = function (key, opts, cb) {
 Multilevel.prototype._batch = function (batch, opts, cb) {
   if (this._db) return this._db._batch(batch, opts, cb)
 
-  var req = {
+  const req = {
     tag: 3,
     id: 0,
     ops: batch,
@@ -217,8 +218,8 @@ Multilevel.prototype._batch = function (batch, opts, cb) {
 
 Multilevel.prototype._write = function (req) {
   if (this._requests.length + this._iterators.length === 1) ref(this._ref)
-  var enc = ENCODERS[req.tag]
-  var buf = Buffer.allocUnsafe(enc.encodingLength(req) + 1)
+  const enc = ENCODERS[req.tag]
+  const buf = Buffer.allocUnsafe(enc.encodingLength(req) + 1)
   buf[0] = req.tag
   enc.encode(req, buf, 1)
   this._encode.write(buf)
@@ -250,7 +251,7 @@ function Iterator (parent, opts) {
   this._valueAsBuffer = opts.valueAsBuffer
   this._options = opts
 
-  var req = {
+  const req = {
     tag: 4,
     id: 0,
     batch: 32,
@@ -279,7 +280,7 @@ Iterator.prototype.next = function (cb) {
       this._parent._write(this._req)
     }
 
-    var next = this._req.pending.shift()
+    const next = this._req.pending.shift()
     if (next.error) return cb(decodeError(next.error))
 
     if (!next.key && !next.value) return cb()
@@ -287,8 +288,8 @@ Iterator.prototype.next = function (cb) {
     this._options.gt = next.key
     if (this._options.limit > 0) this._options.limit--
 
-    var key = decodeValue(next.key, this._keyAsBuffer)
-    var val = decodeValue(next.value, this._valueAsBuffer)
+    const key = decodeValue(next.key, this._keyAsBuffer)
+    const val = decodeValue(next.value, this._valueAsBuffer)
     return cb(undefined, key, val)
   }
 
diff --git a/messages.js b/messages.js
index dde5c24..a14c49f 100644
--- a/messages.js
+++ b/messages.js
@@ -6,53 +6,53 @@
 /* eslint-disable camelcase */
 
 // Remember to `npm install --save protocol-buffers-encodings`
-var encodings = require('protocol-buffers-encodings')
-var varint = encodings.varint
-var skip = encodings.skip
+const encodings = require('protocol-buffers-encodings')
+const varint = encodings.varint
+const skip = encodings.skip
 
-var Get = exports.Get = {
+const Get = exports.Get = {
   buffer: true,
   encodingLength: null,
   encode: null,
   decode: null
 }
 
-var Put = exports.Put = {
+const Put = exports.Put = {
   buffer: true,
   encodingLength: null,
   encode: null,
   decode: null
 }
 
-var Delete = exports.Delete = {
+const Delete = exports.Delete = {
   buffer: true,
   encodingLength: null,
   encode: null,
   decode: null
 }
 
-var Batch = exports.Batch = {
+const Batch = exports.Batch = {
   buffer: true,
   encodingLength: null,
   encode: null,
   decode: null
 }
 
-var Iterator = exports.Iterator = {
+const Iterator = exports.Iterator = {
   buffer: true,
   encodingLength: null,
   encode: null,
   decode: null
 }
 
-var Callback = exports.Callback = {
+const Callback = exports.Callback = {
   buffer: true,
   encodingLength: null,
   encode: null,
   decode: null
 }
 
-var IteratorData = exports.IteratorData = {
+const IteratorData = exports.IteratorData = {
   buffer: true,
   encodingLength: null,
   encode: null,
@@ -68,7 +68,7 @@ defineCallback()
 defineIteratorData()
 
 function defineGet () {
-  var enc = [
+  const enc = [
     encodings.varint,
     encodings.bytes
   ]
@@ -78,20 +78,18 @@ function defineGet () {
   Get.decode = decode
 
   function encodingLength (obj) {
-    var length = 0
+    let length = 0
     if (!defined(obj.id)) throw new Error("id is required")
-    var len = enc[0].encodingLength(obj.id)
-    length += 1 + len
+    length += 1 + enc[0].encodingLength(obj.id)
     if (!defined(obj.key)) throw new Error("key is required")
-    var len = enc[1].encodingLength(obj.key)
-    length += 1 + len
+    length += 1 + enc[1].encodingLength(obj.key)
     return length
   }
 
   function encode (obj, buf, offset) {
     if (!offset) offset = 0
     if (!buf) buf = Buffer.allocUnsafe(encodingLength(obj))
-    var oldOffset = offset
+    const oldOffset = offset
     if (!defined(obj.id)) throw new Error("id is required")
     buf[offset++] = 8
     enc[0].encode(obj.id, buf, offset)
@@ -108,22 +106,22 @@ function defineGet () {
     if (!offset) offset = 0
     if (!end) end = buf.length
     if (!(end <= buf.length && offset <= buf.length)) throw new Error("Decoded message is not valid")
-    var oldOffset = offset
-    var obj = {
+    const oldOffset = offset
+    const obj = {
       id: 0,
       key: null
     }
-    var found0 = false
-    var found1 = false
+    let found0 = false
+    let found1 = false
     while (true) {
       if (end <= offset) {
         if (!found0 || !found1) throw new Error("Decoded message is not valid")
         decode.bytes = offset - oldOffset
         return obj
       }
-      var prefix = varint.decode(buf, offset)
+      const prefix = varint.decode(buf, offset)
       offset += varint.decode.bytes
-      var tag = prefix >> 3
+      const tag = prefix >> 3
       switch (tag) {
         case 1:
         obj.id = enc[0].decode(buf, offset)
@@ -143,7 +141,7 @@ function defineGet () {
 }
 
 function definePut () {
-  var enc = [
+  const enc = [
     encodings.varint,
     encodings.bytes
   ]
@@ -153,16 +151,13 @@ function definePut () {
   Put.decode = decode
 
   function encodingLength (obj) {
-    var length = 0
+    let length = 0
     if (!defined(obj.id)) throw new Error("id is required")
-    var len = enc[0].encodingLength(obj.id)
-    length += 1 + len
+    length += 1 + enc[0].encodingLength(obj.id)
     if (!defined(obj.key)) throw new Error("key is required")
-    var len = enc[1].encodingLength(obj.key)
-    length += 1 + len
+    length += 1 + enc[1].encodingLength(obj.key)
     if (defined(obj.value)) {
-      var len = enc[1].encodingLength(obj.value)
-      length += 1 + len
+      length += 1 + enc[1].encodingLength(obj.value)
     }
     return length
   }
@@ -170,7 +165,7 @@ function definePut () {
   function encode (obj, buf, offset) {
     if (!offset) offset = 0
     if (!buf) buf = Buffer.allocUnsafe(encodingLength(obj))
-    var oldOffset = offset
+    const oldOffset = offset
     if (!defined(obj.id)) throw new Error("id is required")
     buf[offset++] = 8
     enc[0].encode(obj.id, buf, offset)
@@ -192,23 +187,23 @@ function definePut () {
     if (!offset) offset = 0
     if (!end) end = buf.length
     if (!(end <= buf.length && offset <= buf.length)) throw new Error("Decoded message is not valid")
-    var oldOffset = offset
-    var obj = {
+    const oldOffset = offset
+    const obj = {
       id: 0,
       key: null,
       value: null
     }
-    var found0 = false
-    var found1 = false
+    let found0 = false
+    let found1 = false
     while (true) {
       if (end <= offset) {
         if (!found0 || !found1) throw new Error("Decoded message is not valid")
         decode.bytes = offset - oldOffset
         return obj
       }
-      var prefix = varint.decode(buf, offset)
+      const prefix = varint.decode(buf, offset)
       offset += varint.decode.bytes
-      var tag = prefix >> 3
+      const tag = prefix >> 3
       switch (tag) {
         case 1:
         obj.id = enc[0].decode(buf, offset)
@@ -232,7 +227,7 @@ function definePut () {
 }
 
 function defineDelete () {
-  var enc = [
+  const enc = [
     encodings.varint,
     encodings.bytes
   ]
@@ -242,20 +237,18 @@ function defineDelete () {
   Delete.decode = decode
 
   function encodingLength (obj) {
-    var length = 0
+    let length = 0
     if (!defined(obj.id)) throw new Error("id is required")
-    var len = enc[0].encodingLength(obj.id)
-    length += 1 + len
+    length += 1 + enc[0].encodingLength(obj.id)
     if (!defined(obj.key)) throw new Error("key is required")
-    var len = enc[1].encodingLength(obj.key)
-    length += 1 + len
+    length += 1 + enc[1].encodingLength(obj.key)
     return length
   }
 
   function encode (obj, buf, offset) {
     if (!offset) offset = 0
     if (!buf) buf = Buffer.allocUnsafe(encodingLength(obj))
-    var oldOffset = offset
+    const oldOffset = offset
     if (!defined(obj.id)) throw new Error("id is required")
     buf[offset++] = 8
     enc[0].encode(obj.id, buf, offset)
@@ -272,22 +265,22 @@ function defineDelete () {
     if (!offset) offset = 0
     if (!end) end = buf.length
     if (!(end <= buf.length && offset <= buf.length)) throw new Error("Decoded message is not valid")
-    var oldOffset = offset
-    var obj = {
+    const oldOffset = offset
+    const obj = {
       id: 0,
       key: null
     }
-    var found0 = false
-    var found1 = false
+    let found0 = false
+    let found1 = false
     while (true) {
       if (end <= offset) {
         if (!found0 || !found1) throw new Error("Decoded message is not valid")
         decode.bytes = offset - oldOffset
         return obj
       }
-      var prefix = varint.decode(buf, offset)
+      const prefix = varint.decode(buf, offset)
       offset += varint.decode.bytes
-      var tag = prefix >> 3
+      const tag = prefix >> 3
       switch (tag) {
         case 1:
         obj.id = enc[0].decode(buf, offset)
@@ -307,7 +300,7 @@ function defineDelete () {
 }
 
 function defineBatch () {
-  var Operation = Batch.Operation = {
+  const Operation = Batch.Operation = {
     buffer: true,
     encodingLength: null,
     encode: null,
@@ -317,7 +310,7 @@ function defineBatch () {
   defineOperation()
 
   function defineOperation () {
-    var enc = [
+    const enc = [
       encodings.string,
       encodings.bytes
     ]
@@ -327,16 +320,13 @@ function defineBatch () {
     Operation.decode = decode
 
     function encodingLength (obj) {
-      var length = 0
+      let length = 0
       if (!defined(obj.type)) throw new Error("type is required")
-      var len = enc[0].encodingLength(obj.type)
-      length += 1 + len
+      length += 1 + enc[0].encodingLength(obj.type)
       if (!defined(obj.key)) throw new Error("key is required")
-      var len = enc[1].encodingLength(obj.key)
-      length += 1 + len
+      length += 1 + enc[1].encodingLength(obj.key)
       if (defined(obj.value)) {
-        var len = enc[1].encodingLength(obj.value)
-        length += 1 + len
+        length += 1 + enc[1].encodingLength(obj.value)
       }
       return length
     }
@@ -344,7 +334,7 @@ function defineBatch () {
     function encode (obj, buf, offset) {
       if (!offset) offset = 0
       if (!buf) buf = Buffer.allocUnsafe(encodingLength(obj))
-      var oldOffset = offset
+      const oldOffset = offset
       if (!defined(obj.type)) throw new Error("type is required")
       buf[offset++] = 10
       enc[0].encode(obj.type, buf, offset)
@@ -366,23 +356,23 @@ function defineBatch () {
       if (!offset) offset = 0
       if (!end) end = buf.length
       if (!(end <= buf.length && offset <= buf.length)) throw new Error("Decoded message is not valid")
-      var oldOffset = offset
-      var obj = {
+      const oldOffset = offset
+      const obj = {
         type: "",
         key: null,
         value: null
       }
-      var found0 = false
-      var found1 = false
+      let found0 = false
+      let found1 = false
       while (true) {
         if (end <= offset) {
           if (!found0 || !found1) throw new Error("Decoded message is not valid")
           decode.bytes = offset - oldOffset
           return obj
         }
-        var prefix = varint.decode(buf, offset)
+        const prefix = varint.decode(buf, offset)
         offset += varint.decode.bytes
-        var tag = prefix >> 3
+        const tag = prefix >> 3
         switch (tag) {
           case 1:
           obj.type = enc[0].decode(buf, offset)
@@ -405,7 +395,7 @@ function defineBatch () {
     }
   }
 
-  var enc = [
+  const enc = [
     encodings.varint,
     Operation
   ]
@@ -415,14 +405,13 @@ function defineBatch () {
   Batch.decode = decode
 
   function encodingLength (obj) {
-    var length = 0
+    let length = 0
     if (!defined(obj.id)) throw new Error("id is required")
-    var len = enc[0].encodingLength(obj.id)
-    length += 1 + len
+    length += 1 + enc[0].encodingLength(obj.id)
     if (defined(obj.ops)) {
-      for (var i = 0; i < obj.ops.length; i++) {
+      for (let i = 0; i < obj.ops.length; i++) {
         if (!defined(obj.ops[i])) continue
-        var len = enc[1].encodingLength(obj.ops[i])
+        const len = enc[1].encodingLength(obj.ops[i])
         length += varint.encodingLength(len)
         length += 1 + len
       }
@@ -433,13 +422,13 @@ function defineBatch () {
   function encode (obj, buf, offset) {
     if (!offset) offset = 0
     if (!buf) buf = Buffer.allocUnsafe(encodingLength(obj))
-    var oldOffset = offset
+    const oldOffset = offset
     if (!defined(obj.id)) throw new Error("id is required")
     buf[offset++] = 8
     enc[0].encode(obj.id, buf, offset)
     offset += enc[0].encode.bytes
     if (defined(obj.ops)) {
-      for (var i = 0; i < obj.ops.length; i++) {
+      for (let i = 0; i < obj.ops.length; i++) {
         if (!defined(obj.ops[i])) continue
         buf[offset++] = 18
         varint.encode(enc[1].encodingLength(obj.ops[i]), buf, offset)
@@ -456,21 +445,21 @@ function defineBatch () {
     if (!offset) offset = 0
     if (!end) end = buf.length
     if (!(end <= buf.length && offset <= buf.length)) throw new Error("Decoded message is not valid")
-    var oldOffset = offset
-    var obj = {
+    const oldOffset = offset
+    const obj = {
       id: 0,
       ops: []
     }
-    var found0 = false
+    let found0 = false
     while (true) {
       if (end <= offset) {
         if (!found0) throw new Error("Decoded message is not valid")
         decode.bytes = offset - oldOffset
         return obj
       }
-      var prefix = varint.decode(buf, offset)
+      const prefix = varint.decode(buf, offset)
       offset += varint.decode.bytes
-      var tag = prefix >> 3
+      const tag = prefix >> 3
       switch (tag) {
         case 1:
         obj.id = enc[0].decode(buf, offset)
@@ -478,9 +467,8 @@ function defineBatch () {
         found0 = true
         break
         case 2:
-        var len = varint.decode(buf, offset)
         offset += varint.decode.bytes
-        obj.ops.push(enc[1].decode(buf, offset, offset + len))
+        obj.ops.push(enc[1].decode(buf, offset, offset + varint.decode(buf, offset)))
         offset += enc[1].decode.bytes
         break
         default:
@@ -491,7 +479,7 @@ function defineBatch () {
 }
 
 function defineIterator () {
-  var Options = Iterator.Options = {
+  const Options = Iterator.Options = {
     buffer: true,
     encodingLength: null,
     encode: null,
@@ -501,7 +489,7 @@ function defineIterator () {
   defineOptions()
 
   function defineOptions () {
-    var enc = [
+    const enc = [
       encodings.bool,
       encodings.bytes,
       encodings.sint64
@@ -512,38 +500,30 @@ function defineIterator () {
     Options.decode = decode
 
     function encodingLength (obj) {
-      var length = 0
+      let length = 0
       if (defined(obj.keys)) {
-        var len = enc[0].encodingLength(obj.keys)
-        length += 1 + len
+        length += 1 + enc[0].encodingLength(obj.keys)
       }
       if (defined(obj.values)) {
-        var len = enc[0].encodingLength(obj.values)
-        length += 1 + len
+        length += 1 + enc[0].encodingLength(obj.values)
       }
       if (defined(obj.gt)) {
-        var len = enc[1].encodingLength(obj.gt)
-        length += 1 + len
+        length += 1 + enc[1].encodingLength(obj.gt)
       }
       if (defined(obj.gte)) {
-        var len = enc[1].encodingLength(obj.gte)
-        length += 1 + len
+        length += 1 + enc[1].encodingLength(obj.gte)
       }
       if (defined(obj.lt)) {
-        var len = enc[1].encodingLength(obj.lt)
-        length += 1 + len
+        length += 1 + enc[1].encodingLength(obj.lt)
       }
       if (defined(obj.lte)) {
-        var len = enc[1].encodingLength(obj.lte)
-        length += 1 + len
+        length += 1 + enc[1].encodingLength(obj.lte)
       }
       if (defined(obj.limit)) {
-        var len = enc[2].encodingLength(obj.limit)
-        length += 1 + len
+        length += 1 + enc[2].encodingLength(obj.limit)
       }
       if (defined(obj.reverse)) {
-        var len = enc[0].encodingLength(obj.reverse)
-        length += 1 + len
+        length += 1 + enc[0].encodingLength(obj.reverse)
       }
       return length
     }
@@ -551,7 +531,7 @@ function defineIterator () {
     function encode (obj, buf, offset) {
       if (!offset) offset = 0
       if (!buf) buf = Buffer.allocUnsafe(encodingLength(obj))
-      var oldOffset = offset
+      const oldOffset = offset
       if (defined(obj.keys)) {
         buf[offset++] = 8
         enc[0].encode(obj.keys, buf, offset)
@@ -600,8 +580,8 @@ function defineIterator () {
       if (!offset) offset = 0
       if (!end) end = buf.length
       if (!(end <= buf.length && offset <= buf.length)) throw new Error("Decoded message is not valid")
-      var oldOffset = offset
-      var obj = {
+      const oldOffset = offset
+      const obj = {
         keys: false,
         values: false,
         gt: null,
@@ -616,9 +596,9 @@ function defineIterator () {
           decode.bytes = offset - oldOffset
           return obj
         }
-        var prefix = varint.decode(buf, offset)
+        const prefix = varint.decode(buf, offset)
         offset += varint.decode.bytes
-        var tag = prefix >> 3
+        const tag = prefix >> 3
         switch (tag) {
           case 1:
           obj.keys = enc[0].decode(buf, offset)
@@ -659,7 +639,7 @@ function defineIterator () {
     }
   }
 
-  var enc = [
+  const enc = [
     encodings.varint,
     Options
   ]
@@ -669,16 +649,14 @@ function defineIterator () {
   Iterator.decode = decode
 
   function encodingLength (obj) {
-    var length = 0
+    let length = 0
     if (!defined(obj.id)) throw new Error("id is required")
-    var len = enc[0].encodingLength(obj.id)
-    length += 1 + len
+    length += 1 + enc[0].encodingLength(obj.id)
     if (defined(obj.batch)) {
-      var len = enc[0].encodingLength(obj.batch)
-      length += 1 + len
+      length += 1 + enc[0].encodingLength(obj.batch)
     }
     if (defined(obj.options)) {
-      var len = enc[1].encodingLength(obj.options)
+      const len = enc[1].encodingLength(obj.options)
       length += varint.encodingLength(len)
       length += 1 + len
     }
@@ -688,7 +666,7 @@ function defineIterator () {
   function encode (obj, buf, offset) {
     if (!offset) offset = 0
     if (!buf) buf = Buffer.allocUnsafe(encodingLength(obj))
-    var oldOffset = offset
+    const oldOffset = offset
     if (!defined(obj.id)) throw new Error("id is required")
     buf[offset++] = 8
     enc[0].encode(obj.id, buf, offset)
@@ -713,22 +691,22 @@ function defineIterator () {
     if (!offset) offset = 0
     if (!end) end = buf.length
     if (!(end <= buf.length && offset <= buf.length)) throw new Error("Decoded message is not valid")
-    var oldOffset = offset
-    var obj = {
+    const oldOffset = offset
+    const obj = {
       id: 0,
       batch: 0,
       options: null
     }
-    var found0 = false
+    let found0 = false
     while (true) {
       if (end <= offset) {
         if (!found0) throw new Error("Decoded message is not valid")
         decode.bytes = offset - oldOffset
         return obj
       }
-      var prefix = varint.decode(buf, offset)
+      const prefix = varint.decode(buf, offset)
       offset += varint.decode.bytes
-      var tag = prefix >> 3
+      const tag = prefix >> 3
       switch (tag) {
         case 1:
         obj.id = enc[0].decode(buf, offset)
@@ -740,9 +718,8 @@ function defineIterator () {
         offset += enc[0].decode.bytes
         break
         case 3:
-        var len = varint.decode(buf, offset)
         offset += varint.decode.bytes
-        obj.options = enc[1].decode(buf, offset, offset + len)
+        obj.options = enc[1].decode(buf, offset, offset + varint.decode(buf, offset))
         offset += enc[1].decode.bytes
         break
         default:
@@ -753,7 +730,7 @@ function defineIterator () {
 }
 
 function defineCallback () {
-  var enc = [
+  const enc = [
     encodings.varint,
     encodings.string,
     encodings.bytes
@@ -764,17 +741,14 @@ function defineCallback () {
   Callback.decode = decode
 
   function encodingLength (obj) {
-    var length = 0
+    let length = 0
     if (!defined(obj.id)) throw new Error("id is required")
-    var len = enc[0].encodingLength(obj.id)
-    length += 1 + len
+    length += 1 + enc[0].encodingLength(obj.id)
     if (defined(obj.error)) {
-      var len = enc[1].encodingLength(obj.error)
-      length += 1 + len
+      length += 1 + enc[1].encodingLength(obj.error)
     }
     if (defined(obj.value)) {
-      var len = enc[2].encodingLength(obj.value)
-      length += 1 + len
+      length += 1 + enc[2].encodingLength(obj.value)
     }
     return length
   }
@@ -782,7 +756,7 @@ function defineCallback () {
   function encode (obj, buf, offset) {
     if (!offset) offset = 0
     if (!buf) buf = Buffer.allocUnsafe(encodingLength(obj))
-    var oldOffset = offset
+    const oldOffset = offset
     if (!defined(obj.id)) throw new Error("id is required")
     buf[offset++] = 8
     enc[0].encode(obj.id, buf, offset)
@@ -805,22 +779,22 @@ function defineCallback () {
     if (!offset) offset = 0
     if (!end) end = buf.length
     if (!(end <= buf.length && offset <= buf.length)) throw new Error("Decoded message is not valid")
-    var oldOffset = offset
-    var obj = {
+    const oldOffset = offset
+    const obj = {
       id: 0,
       error: "",
       value: null
     }
-    var found0 = false
+    let found0 = false
     while (true) {
       if (end <= offset) {
         if (!found0) throw new Error("Decoded message is not valid")
         decode.bytes = offset - oldOffset
         return obj
       }
-      var prefix = varint.decode(buf, offset)
+      const prefix = varint.decode(buf, offset)
       offset += varint.decode.bytes
-      var tag = prefix >> 3
+      const tag = prefix >> 3
       switch (tag) {
         case 1:
         obj.id = enc[0].decode(buf, offset)
@@ -843,7 +817,7 @@ function defineCallback () {
 }
 
 function defineIteratorData () {
-  var enc = [
+  const enc = [
     encodings.varint,
     encodings.string,
     encodings.bytes
@@ -854,21 +828,17 @@ function defineIteratorData () {
   IteratorData.decode = decode
 
   function encodingLength (obj) {
-    var length = 0
+    let length = 0
     if (!defined(obj.id)) throw new Error("id is required")
-    var len = enc[0].encodingLength(obj.id)
-    length += 1 + len
+    length += 1 + enc[0].encodingLength(obj.id)
     if (defined(obj.error)) {
-      var len = enc[1].encodingLength(obj.error)
-      length += 1 + len
+      length += 1 + enc[1].encodingLength(obj.error)
     }
     if (defined(obj.key)) {
-      var len = enc[2].encodingLength(obj.key)
-      length += 1 + len
+      length += 1 + enc[2].encodingLength(obj.key)
     }
     if (defined(obj.value)) {
-      var len = enc[2].encodingLength(obj.value)
-      length += 1 + len
+      length += 1 + enc[2].encodingLength(obj.value)
     }
     return length
   }
@@ -876,7 +846,7 @@ function defineIteratorData () {
   function encode (obj, buf, offset) {
     if (!offset) offset = 0
     if (!buf) buf = Buffer.allocUnsafe(encodingLength(obj))
-    var oldOffset = offset
+    const oldOffset = offset
     if (!defined(obj.id)) throw new Error("id is required")
     buf[offset++] = 8
     enc[0].encode(obj.id, buf, offset)
@@ -904,23 +874,23 @@ function defineIteratorData () {
     if (!offset) offset = 0
     if (!end) end = buf.length
     if (!(end <= buf.length && offset <= buf.length)) throw new Error("Decoded message is not valid")
-    var oldOffset = offset
-    var obj = {
+    const oldOffset = offset
+    const obj = {
       id: 0,
       error: "",
       key: null,
       value: null
     }
-    var found0 = false
+    let found0 = false
     while (true) {
       if (end <= offset) {
         if (!found0) throw new Error("Decoded message is not valid")
         decode.bytes = offset - oldOffset
         return obj
       }
-      var prefix = varint.decode(buf, offset)
+      const prefix = varint.decode(buf, offset)
       offset += varint.decode.bytes
-      var tag = prefix >> 3
+      const tag = prefix >> 3
       switch (tag) {
         case 1:
         obj.id = enc[0].decode(buf, offset)
diff --git a/package.json b/package.json
index 735c313..abc5e4e 100644
--- a/package.json
+++ b/package.json
@@ -34,9 +34,9 @@
     "level-community": "^3.0.0",
     "level-compose": "^0.0.2",
     "memdown": "^5.0.0",
-    "nyc": "^14.1.1",
+    "nyc": "^15.1.0",
     "protocol-buffers": "^4.0.2",
-    "standard": "^14.1.0",
+    "standard": "^16.0.3",
     "subleveldown": "^5.0.1",
     "tape": "^5.0.1"
   },
diff --git a/server.js b/server.js
index ec74bc5..3fe0825 100644
--- a/server.js
+++ b/server.js
@@ -1,12 +1,12 @@
-var lpstream = require('length-prefixed-stream')
-var eos = require('end-of-stream')
-var duplexify = require('duplexify')
-var reachdown = require('reachdown')
-var messages = require('./messages')
-var rangeOptions = 'gt gte lt lte'.split(' ')
-var matchdown = require('./matchdown')
-
-var DECODERS = [
+const lpstream = require('length-prefixed-stream')
+const eos = require('end-of-stream')
+const duplexify = require('duplexify')
+const reachdown = require('reachdown')
+const messages = require('./messages')
+const rangeOptions = 'gt gte lt lte'.split(' ')
+const matchdown = require('./matchdown')
+
+const DECODERS = [
   messages.Get,
   messages.Put,
   messages.Delete,
@@ -17,14 +17,14 @@ var DECODERS = [
 module.exports = function (db, opts) {
   if (!opts) opts = {}
 
-  var readonly = !!(opts.readonly)
-  var decode = lpstream.decode()
-  var encode = lpstream.encode()
-  var stream = duplexify(decode, encode)
+  const readonly = !!(opts.readonly)
+  const decode = lpstream.decode()
+  const encode = lpstream.encode()
+  const stream = duplexify(decode, encode)
 
-  var preput = opts.preput || function (key, val, cb) { cb(null) }
-  var predel = opts.predel || function (key, cb) { cb(null) }
-  var prebatch = opts.prebatch || function (ops, cb) { cb(null) }
+  const preput = opts.preput || function (key, val, cb) { cb(null) }
+  const predel = opts.predel || function (key, cb) { cb(null) }
+  const prebatch = opts.prebatch || function (ops, cb) { cb(null) }
 
   if (db.isOpen()) ready()
   else db.open(ready)
@@ -32,24 +32,25 @@ module.exports = function (db, opts) {
   return stream
 
   function ready () {
-    var down = reachdown(db, matchdown, false)
-    var iterators = []
+    const down = reachdown(db, matchdown, false)
+    const iterators = []
 
     eos(stream, function () {
       while (iterators.length) {
-        var next = iterators.shift()
+        const next = iterators.shift()
         if (next) next.end()
       }
     })
 
     decode.on('data', function (data) {
       if (!data.length) return
-      var tag = data[0]
+      const tag = data[0]
       if (tag >= DECODERS.length) return
 
-      var dec = DECODERS[tag]
+      const dec = DECODERS[tag]
+      let req
       try {
-        var req = dec.decode(data, 1)
+        req = dec.decode(data, 1)
       } catch (err) {
         return
       }
@@ -74,8 +75,8 @@ module.exports = function (db, opts) {
     })
 
     function callback (id, err, value) {
-      var msg = { id: id, error: err && err.message, value: value }
-      var buf = Buffer.allocUnsafe(messages.Callback.encodingLength(msg) + 1)
+      const msg = { id: id, error: err && err.message, value: value }
+      const buf = Buffer.allocUnsafe(messages.Callback.encodingLength(msg) + 1)
       buf[0] = 0
       messages.Callback.encode(msg, buf, 1)
       encode.write(buf)
@@ -122,7 +123,7 @@ module.exports = function (db, opts) {
     function oniterator (req) {
       while (iterators.length < req.id) iterators.push(null)
 
-      var prev = iterators[req.id]
+      let prev = iterators[req.id]
       if (!prev) prev = iterators[req.id] = new Iterator(down, req, encode)
 
       if (!req.batch) {
@@ -137,7 +138,7 @@ module.exports = function (db, opts) {
 }
 
 function Iterator (down, req, encode) {
-  var self = this
+  const self = this
 
   this.batch = req.batch || 0
   this._iterator = down.iterator(cleanRangeOptions(req.options))
@@ -159,7 +160,7 @@ function Iterator (down, req, encode) {
     self._data.key = key
     self._data.value = value
     self.batch--
-    var buf = Buffer.allocUnsafe(messages.IteratorData.encodingLength(self._data) + 1)
+    const buf = Buffer.allocUnsafe(messages.IteratorData.encodingLength(self._data) + 1)
     buf[0] = 1
     messages.IteratorData.encode(self._data, buf, 1)
     encode.write(buf)
@@ -185,9 +186,9 @@ function noop () {}
 function cleanRangeOptions (options) {
   if (!options) return
 
-  var result = {}
+  const result = {}
 
-  for (var k in options) {
+  for (const k in options) {
     if (!hasOwnProperty.call(options, k)) continue
 
     if (!isRangeOption(k) || options[k] != null) {
diff --git a/streams.js b/streams.js
index 9b275ab..642b412 100644
--- a/streams.js
+++ b/streams.js
@@ -1,5 +1,5 @@
-var pbs = require('pbs')
-var fs = require('fs')
-var path = require('path')
+const pbs = require('pbs')
+const fs = require('fs')
+const path = require('path')
 
 module.exports = pbs(fs.readFileSync(path.join(__dirname, 'schema.proto')))
diff --git a/test/abstract.js b/test/abstract.js
index a6a5b96..b53cbc9 100644
--- a/test/abstract.js
+++ b/test/abstract.js
@@ -1,17 +1,17 @@
-var test = require('tape')
-var memdown = require('memdown')
-var levelup = require('levelup')
-var encode = require('encoding-down')
-var factory = require('level-compose')(memdown, encode, levelup)
-var multileveldown = require('..')
-var suite = require('abstract-leveldown/test')
+const test = require('tape')
+const memdown = require('memdown')
+const levelup = require('levelup')
+const encode = require('encoding-down')
+const factory = require('level-compose')(memdown, encode, levelup)
+const multileveldown = require('..')
+const suite = require('abstract-leveldown/test')
 
 suite({
   test: test,
   factory: function () {
-    var db = factory()
-    var stream = multileveldown.server(db)
-    var client = multileveldown.client()
+    const db = factory()
+    const stream = multileveldown.server(db)
+    const client = multileveldown.client()
 
     stream.pipe(client.createRpcStream()).pipe(stream)
 
diff --git a/test/basic.js b/test/basic.js
index 653447c..e7a9738 100644
--- a/test/basic.js
+++ b/test/basic.js
@@ -1,17 +1,17 @@
-var tape = require('tape')
-var memdown = require('memdown')
-var concat = require('concat-stream')
-var levelup = require('levelup')
-var encode = require('encoding-down')
-var factory = require('level-compose')(memdown, encode, levelup)
-var multileveldown = require('../')
+const tape = require('tape')
+const memdown = require('memdown')
+const concat = require('concat-stream')
+const levelup = require('levelup')
+const encode = require('encoding-down')
+const factory = require('level-compose')(memdown, encode, levelup)
+const multileveldown = require('../')
 
 tape('get', function (t) {
   t.plan(7)
 
-  var db = factory()
-  var stream = multileveldown.server(db)
-  var client = multileveldown.client()
+  const db = factory()
+  const stream = multileveldown.server(db)
+  const client = multileveldown.client()
 
   stream.pipe(client.createRpcStream()).pipe(stream)
 
@@ -36,9 +36,9 @@ tape('get', function (t) {
 })
 
 tape('get with valueEncoding: json in constructor', function (t) {
-  var db = factory()
-  var stream = multileveldown.server(db)
-  var client = multileveldown.client({ valueEncoding: 'json' })
+  const db = factory()
+  const stream = multileveldown.server(db)
+  const client = multileveldown.client({ valueEncoding: 'json' })
 
   stream.pipe(client.createRpcStream()).pipe(stream)
 
@@ -54,9 +54,9 @@ tape('get with valueEncoding: json in constructor', function (t) {
 tape('get with valueEncoding: json in get options', function (t) {
   t.plan(5)
 
-  var db = factory()
-  var stream = multileveldown.server(db)
-  var client = multileveldown.client()
+  const db = factory()
+  const stream = multileveldown.server(db)
+  const client = multileveldown.client()
 
   stream.pipe(client.createRpcStream()).pipe(stream)
 
@@ -76,9 +76,9 @@ tape('get with valueEncoding: json in get options', function (t) {
 })
 
 tape('put', function (t) {
-  var db = factory()
-  var stream = multileveldown.server(db)
-  var client = multileveldown.client()
+  const db = factory()
+  const stream = multileveldown.server(db)
+  const client = multileveldown.client()
 
   stream.pipe(client.createRpcStream()).pipe(stream)
 
@@ -95,9 +95,9 @@ tape('put', function (t) {
 tape('put with valueEncoding: json in constructor', function (t) {
   t.plan(5)
 
-  var db = factory()
-  var stream = multileveldown.server(db)
-  var client = multileveldown.client({ valueEncoding: 'json' })
+  const db = factory()
+  const stream = multileveldown.server(db)
+  const client = multileveldown.client({ valueEncoding: 'json' })
 
   stream.pipe(client.createRpcStream()).pipe(stream)
 
@@ -119,9 +119,9 @@ tape('put with valueEncoding: json in constructor', function (t) {
 tape('put with valueEncoding: json in put options', function (t) {
   t.plan(5)
 
-  var db = factory()
-  var stream = multileveldown.server(db)
-  var client = multileveldown.client()
+  const db = factory()
+  const stream = multileveldown.server(db)
+  const client = multileveldown.client()
 
   stream.pipe(client.createRpcStream()).pipe(stream)
 
@@ -141,12 +141,12 @@ tape('put with valueEncoding: json in put options', function (t) {
 })
 
 tape('readonly', function (t) {
-  var db = factory()
+  const db = factory()
 
   db.put('hello', 'verden')
 
-  var stream = multileveldown.server(db, { readonly: true })
-  var client = multileveldown.client()
+  const stream = multileveldown.server(db, { readonly: true })
+  const client = multileveldown.client()
 
   stream.pipe(client.createRpcStream()).pipe(stream)
 
@@ -161,9 +161,9 @@ tape('readonly', function (t) {
 })
 
 tape('del', function (t) {
-  var db = factory()
-  var stream = multileveldown.server(db)
-  var client = multileveldown.client()
+  const db = factory()
+  const stream = multileveldown.server(db)
+  const client = multileveldown.client()
 
   stream.pipe(client.createRpcStream()).pipe(stream)
 
@@ -181,9 +181,9 @@ tape('del', function (t) {
 })
 
 tape('batch', function (t) {
-  var db = factory()
-  var stream = multileveldown.server(db)
-  var client = multileveldown.client()
+  const db = factory()
+  const stream = multileveldown.server(db)
+  const client = multileveldown.client()
 
   stream.pipe(client.createRpcStream()).pipe(stream)
 
@@ -202,15 +202,15 @@ tape('batch', function (t) {
 })
 
 tape('read stream', function (t) {
-  var db = factory()
-  var stream = multileveldown.server(db)
-  var client = multileveldown.client()
+  const db = factory()
+  const stream = multileveldown.server(db)
+  const client = multileveldown.client()
 
   stream.pipe(client.createRpcStream()).pipe(stream)
 
   client.batch([{ type: 'put', key: 'hello', value: 'world' }, { type: 'put', key: 'hej', value: 'verden' }], function (err) {
     t.error(err, 'no err')
-    var rs = client.createReadStream()
+    const rs = client.createReadStream()
     rs.pipe(concat(function (datas) {
       t.same(datas.length, 2)
       t.same(datas[0], { key: 'hej', value: 'verden' })
@@ -221,15 +221,15 @@ tape('read stream', function (t) {
 })
 
 tape('read stream (gt)', function (t) {
-  var db = factory()
-  var stream = multileveldown.server(db)
-  var client = multileveldown.client()
+  const db = factory()
+  const stream = multileveldown.server(db)
+  const client = multileveldown.client()
 
   stream.pipe(client.createRpcStream()).pipe(stream)
 
   client.batch([{ type: 'put', key: 'hello', value: 'world' }, { type: 'put', key: 'hej', value: 'verden' }], function (err) {
     t.error(err, 'no err')
-    var rs = client.createReadStream({ gt: 'hej' })
+    const rs = client.createReadStream({ gt: 'hej' })
     rs.pipe(concat(function (datas) {
       t.same(datas.length, 1)
       t.same(datas[0], { key: 'hello', value: 'world' })
diff --git a/test/concurrent.js b/test/concurrent.js
index e3290c7..4724f98 100644
--- a/test/concurrent.js
+++ b/test/concurrent.js
@@ -1,26 +1,26 @@
-var tape = require('tape')
-var memdown = require('memdown')
-var levelup = require('levelup')
-var concat = require('concat-stream')
-var multileveldown = require('../')
-var encode = require('encoding-down')
-var factory = require('level-compose')(memdown, encode, levelup)
+const tape = require('tape')
+const memdown = require('memdown')
+const levelup = require('levelup')
+const concat = require('concat-stream')
+const multileveldown = require('../')
+const encode = require('encoding-down')
+const factory = require('level-compose')(memdown, encode, levelup)
 
 tape('two concurrent iterators', function (t) {
-  var db = factory()
-  var server = multileveldown.server(db)
-  var client = multileveldown.client()
+  const db = factory()
+  const server = multileveldown.server(db)
+  const client = multileveldown.client()
 
   server.pipe(client.connect()).pipe(server)
 
-  var batch = []
-  for (var i = 0; i < 100; i++) batch.push({ type: 'put', key: 'key-' + i, value: 'value-' + i })
+  const batch = []
+  for (let i = 0; i < 100; i++) batch.push({ type: 'put', key: 'key-' + i, value: 'value-' + i })
 
   client.batch(batch, function (err) {
     t.error(err)
 
-    var rs1 = client.createReadStream()
-    var rs2 = client.createReadStream()
+    const rs1 = client.createReadStream()
+    const rs2 = client.createReadStream()
 
     rs1.pipe(concat(function (list1) {
       t.same(list1.length, 100)
diff --git a/test/encryptdown.js b/test/encryptdown.js
index 795f19f..73bd568 100644
--- a/test/encryptdown.js
+++ b/test/encryptdown.js
@@ -1,13 +1,13 @@
-var tape = require('tape')
-var memdown = require('memdown')
-var concat = require('concat-stream')
-var levelup = require('levelup')
-var encode = require('encoding-down')
-var encrypt = require('@adorsys/encrypt-down')
-var factory = require('level-compose')(memdown, encrypt, encode, levelup)
-var multileveldown = require('../')
+const tape = require('tape')
+const memdown = require('memdown')
+const concat = require('concat-stream')
+const levelup = require('levelup')
+const encode = require('encoding-down')
+const encrypt = require('@adorsys/encrypt-down')
+const factory = require('level-compose')(memdown, encrypt, encode, levelup)
+const multileveldown = require('../')
 
-var jwk = {
+const jwk = {
   kty: 'oct',
   alg: 'A256GCM',
   use: 'enc',
@@ -21,9 +21,9 @@ var jwk = {
 tape('multileveldown server on encrypt-down', function (t) {
   t.plan(3)
 
-  var db = factory({ jwk })
-  var stream = multileveldown.server(db)
-  var client = multileveldown.client()
+  const db = factory({ jwk })
+  const stream = multileveldown.server(db)
+  const client = multileveldown.client()
 
   stream.pipe(client.createRpcStream()).pipe(stream)
 
@@ -46,9 +46,9 @@ tape('multileveldown server on encrypt-down', function (t) {
 tape('multileveldown server on encrypt-down with encoding', function (t) {
   t.plan(3)
 
-  var db = factory({ jwk, valueEncoding: 'json' })
-  var stream = multileveldown.server(db)
-  var client = multileveldown.client({ valueEncoding: 'json' })
+  const db = factory({ jwk, valueEncoding: 'json' })
+  const stream = multileveldown.server(db)
+  const client = multileveldown.client({ valueEncoding: 'json' })
 
   stream.pipe(client.createRpcStream()).pipe(stream)
 
diff --git a/test/retry.js b/test/retry.js
index 8dee6df..9ea4b85 100644
--- a/test/retry.js
+++ b/test/retry.js
@@ -1,14 +1,14 @@
-var tape = require('tape')
-var memdown = require('memdown')
-var levelup = require('levelup')
-var multileveldown = require('../')
-var encode = require('encoding-down')
-var factory = require('level-compose')(memdown, encode, levelup)
+const tape = require('tape')
+const memdown = require('memdown')
+const levelup = require('levelup')
+const multileveldown = require('../')
+const encode = require('encoding-down')
+const factory = require('level-compose')(memdown, encode, levelup)
 
 tape('retry get', function (t) {
-  var db = factory()
-  var stream = multileveldown.server(db)
-  var client = multileveldown.client({ retry: true })
+  const db = factory()
+  const stream = multileveldown.server(db)
+  const client = multileveldown.client({ retry: true })
 
   db.put('hello', 'world', function () {
     client.get('hello', function (err, value) {
@@ -22,9 +22,9 @@ tape('retry get', function (t) {
 })
 
 tape('no retry get', function (t) {
-  var db = factory()
-  var stream = multileveldown.server(db)
-  var client = multileveldown.client({ retry: false })
+  const db = factory()
+  const stream = multileveldown.server(db)
+  const client = multileveldown.client({ retry: false })
 
   client.open(function () {
     db.put('hello', 'world', function () {
@@ -33,12 +33,12 @@ tape('no retry get', function (t) {
         t.end()
       })
 
-      var rpc = client.createRpcStream()
+      const rpc = client.createRpcStream()
       stream.pipe(rpc).pipe(stream)
       rpc.destroy()
 
       setTimeout(function () {
-        var rpc = client.createRpcStream()
+        const rpc = client.createRpcStream()
         stream.pipe(rpc).pipe(stream)
       }, 100)
     })
@@ -46,9 +46,9 @@ tape('no retry get', function (t) {
 })
 
 tape('retry get', function (t) {
-  var db = factory()
-  var stream = multileveldown.server(db)
-  var client = multileveldown.client({ retry: true })
+  const db = factory()
+  const stream = multileveldown.server(db)
+  const client = multileveldown.client({ retry: true })
 
   client.open(function () {
     db.put('hello', 'world', function () {
@@ -58,12 +58,12 @@ tape('retry get', function (t) {
         t.end()
       })
 
-      var rpc = client.createRpcStream()
+      const rpc = client.createRpcStream()
       stream.pipe(rpc).pipe(stream)
       rpc.destroy()
 
       setTimeout(function () {
-        var rpc = client.createRpcStream()
+        const rpc = client.createRpcStream()
         stream.pipe(rpc).pipe(stream)
       }, 100)
     })
@@ -71,8 +71,8 @@ tape('retry get', function (t) {
 })
 
 tape('retry read stream', function (t) {
-  var db = factory()
-  var client = multileveldown.client({ retry: true })
+  const db = factory()
+  const client = multileveldown.client({ retry: true })
 
   client.open(function () {
     db.batch([{
@@ -88,8 +88,8 @@ tape('retry read stream', function (t) {
       key: 'hola',
       value: 'mundo'
     }], function () {
-      var rs = client.createReadStream()
-      var expected = [{
+      const rs = client.createReadStream()
+      const expected = [{
         key: 'hej',
         value: 'verden'
       }, {
@@ -109,10 +109,10 @@ tape('retry read stream', function (t) {
         t.end()
       })
 
-      var stream
-      var clientStream
+      let stream
+      let clientStream
 
-      var connect = function () {
+      const connect = function () {
         stream = multileveldown.server(db)
         clientStream = client.createRpcStream()
 
@@ -126,8 +126,8 @@ tape('retry read stream', function (t) {
 })
 
 tape('retry read stream and limit', function (t) {
-  var db = factory()
-  var client = multileveldown.client({ retry: true })
+  const db = factory()
+  const client = multileveldown.client({ retry: true })
 
   client.open(function () {
     db.batch([{
@@ -143,8 +143,8 @@ tape('retry read stream and limit', function (t) {
       key: 'hola',
       value: 'mundo'
     }], function () {
-      var rs = client.createReadStream({ limit: 2 })
-      var expected = [{
+      const rs = client.createReadStream({ limit: 2 })
+      const expected = [{
         key: 'hej',
         value: 'verden'
       }, {
@@ -161,10 +161,10 @@ tape('retry read stream and limit', function (t) {
         t.end()
       })
 
-      var stream
-      var clientStream
+      let stream
+      let clientStream
 
-      var connect = function () {
+      const connect = function () {
         stream = multileveldown.server(db)
         clientStream = client.createRpcStream()
 
diff --git a/test/streams.js b/test/streams.js
index e3290c7..4724f98 100644
--- a/test/streams.js
+++ b/test/streams.js
@@ -1,26 +1,26 @@
-var tape = require('tape')
-var memdown = require('memdown')
-var levelup = require('levelup')
-var concat = require('concat-stream')
-var multileveldown = require('../')
-var encode = require('encoding-down')
-var factory = require('level-compose')(memdown, encode, levelup)
+const tape = require('tape')
+const memdown = require('memdown')
+const levelup = require('levelup')
+const concat = require('concat-stream')
+const multileveldown = require('../')
+const encode = require('encoding-down')
+const factory = require('level-compose')(memdown, encode, levelup)
 
 tape('two concurrent iterators', function (t) {
-  var db = factory()
-  var server = multileveldown.server(db)
-  var client = multileveldown.client()
+  const db = factory()
+  const server = multileveldown.server(db)
+  const client = multileveldown.client()
 
   server.pipe(client.connect()).pipe(server)
 
-  var batch = []
-  for (var i = 0; i < 100; i++) batch.push({ type: 'put', key: 'key-' + i, value: 'value-' + i })
+  const batch = []
+  for (let i = 0; i < 100; i++) batch.push({ type: 'put', key: 'key-' + i, value: 'value-' + i })
 
   client.batch(batch, function (err) {
     t.error(err)
 
-    var rs1 = client.createReadStream()
-    var rs2 = client.createReadStream()
+    const rs1 = client.createReadStream()
+    const rs2 = client.createReadStream()
 
     rs1.pipe(concat(function (list1) {
       t.same(list1.length, 100)
diff --git a/test/subleveldown.js b/test/subleveldown.js
index e4cafe7..be1c381 100644
--- a/test/subleveldown.js
+++ b/test/subleveldown.js
@@ -1,20 +1,20 @@
-var tape = require('tape')
-var memdown = require('memdown')
-var concat = require('concat-stream')
-var levelup = require('levelup')
-var encode = require('encoding-down')
-var factory = require('level-compose')(memdown, encode, levelup)
-var sub = require('subleveldown')
-var multileveldown = require('../')
+const tape = require('tape')
+const memdown = require('memdown')
+const concat = require('concat-stream')
+const levelup = require('levelup')
+const encode = require('encoding-down')
+const factory = require('level-compose')(memdown, encode, levelup)
+const sub = require('subleveldown')
+const multileveldown = require('../')
 
 tape('subleveldown on deferred multileveldown client', function (t) {
   t.plan(5)
 
-  var db = factory()
-  var stream = multileveldown.server(db)
-  var client = multileveldown.client()
-  var sub1 = sub(client, 'test', { valueEncoding: 'json' })
-  var sub2 = sub(client, 'test')
+  const db = factory()
+  const stream = multileveldown.server(db)
+  const client = multileveldown.client()
+  const sub1 = sub(client, 'test', { valueEncoding: 'json' })
+  const sub2 = sub(client, 'test')
 
   t.is(client.isOpen(), false)
   stream.pipe(client.createRpcStream()).pipe(stream)
@@ -39,17 +39,17 @@ tape('subleveldown on deferred multileveldown client', function (t) {
 tape('subleveldown on non-deferred multileveldown client', function (t) {
   t.plan(5)
 
-  var db = factory()
-  var stream = multileveldown.server(db)
-  var client = multileveldown.client()
+  const db = factory()
+  const stream = multileveldown.server(db)
+  const client = multileveldown.client()
 
   stream.pipe(client.createRpcStream()).pipe(stream)
 
   client.once('open', function () {
     t.is(client.isOpen(), true)
 
-    var sub1 = sub(client, 'test', { valueEncoding: 'json' })
-    var sub2 = sub(client, 'test')
+    const sub1 = sub(client, 'test', { valueEncoding: 'json' })
+    const sub2 = sub(client, 'test')
 
     sub1.put('hello', { test: 'world' }, function (err) {
       t.error(err, 'no err')
@@ -72,11 +72,11 @@ tape('subleveldown on non-deferred multileveldown client', function (t) {
 tape('multileveldown server on deferred subleveldown', function (t) {
   t.plan(4)
 
-  var db = factory()
-  var sub1 = sub(db, 'test1')
-  var sub2 = sub(db, 'test2')
-  var stream = multileveldown.server(sub1)
-  var client = multileveldown.client()
+  const db = factory()
+  const sub1 = sub(db, 'test1')
+  const sub2 = sub(db, 'test2')
+  const stream = multileveldown.server(sub1)
+  const client = multileveldown.client()
 
   stream.pipe(client.createRpcStream()).pipe(stream)
 
@@ -103,13 +103,13 @@ tape('multileveldown server on deferred subleveldown', function (t) {
 tape('multileveldown server on non-deferred subleveldown', function (t) {
   t.plan(4)
 
-  var db = factory()
-  var sub1 = sub(db, 'test1')
-  var sub2 = sub(db, 'test2')
+  const db = factory()
+  const sub1 = sub(db, 'test1')
+  const sub2 = sub(db, 'test2')
 
   sub1.once('open', function () {
-    var stream = multileveldown.server(sub1)
-    var client = multileveldown.client()
+    const stream = multileveldown.server(sub1)
+    const client = multileveldown.client()
 
     stream.pipe(client.createRpcStream()).pipe(stream)
 
@@ -137,12 +137,12 @@ tape('multileveldown server on non-deferred subleveldown', function (t) {
 tape('multileveldown server on nested subleveldown', function (t) {
   t.plan(4)
 
-  var db = factory()
-  var sub1 = sub(db, 'test1')
-  var sub2 = sub(sub1, 'test2')
-  var sub3 = sub(db, 'test3')
-  var stream = multileveldown.server(sub2)
-  var client = multileveldown.client()
+  const db = factory()
+  const sub1 = sub(db, 'test1')
+  const sub2 = sub(sub1, 'test2')
+  const sub3 = sub(db, 'test3')
+  const stream = multileveldown.server(sub2)
+  const client = multileveldown.client()
 
   stream.pipe(client.createRpcStream()).pipe(stream)
 

From 3cde1b2f73f334cdf9141bd9fe1765a8f1f67e64 Mon Sep 17 00:00:00 2001
From: Robert Nagy <ronagy@icloud.com>
Date: Sun, 7 Mar 2021 22:10:19 +0100
Subject: [PATCH 2/2] fixup: ignore messages.js

---
 messages.js  | 272 ++++++++++++++++++++++++++++-----------------------
 package.json |   7 +-
 2 files changed, 157 insertions(+), 122 deletions(-)

diff --git a/messages.js b/messages.js
index a14c49f..dde5c24 100644
--- a/messages.js
+++ b/messages.js
@@ -6,53 +6,53 @@
 /* eslint-disable camelcase */
 
 // Remember to `npm install --save protocol-buffers-encodings`
-const encodings = require('protocol-buffers-encodings')
-const varint = encodings.varint
-const skip = encodings.skip
+var encodings = require('protocol-buffers-encodings')
+var varint = encodings.varint
+var skip = encodings.skip
 
-const Get = exports.Get = {
+var Get = exports.Get = {
   buffer: true,
   encodingLength: null,
   encode: null,
   decode: null
 }
 
-const Put = exports.Put = {
+var Put = exports.Put = {
   buffer: true,
   encodingLength: null,
   encode: null,
   decode: null
 }
 
-const Delete = exports.Delete = {
+var Delete = exports.Delete = {
   buffer: true,
   encodingLength: null,
   encode: null,
   decode: null
 }
 
-const Batch = exports.Batch = {
+var Batch = exports.Batch = {
   buffer: true,
   encodingLength: null,
   encode: null,
   decode: null
 }
 
-const Iterator = exports.Iterator = {
+var Iterator = exports.Iterator = {
   buffer: true,
   encodingLength: null,
   encode: null,
   decode: null
 }
 
-const Callback = exports.Callback = {
+var Callback = exports.Callback = {
   buffer: true,
   encodingLength: null,
   encode: null,
   decode: null
 }
 
-const IteratorData = exports.IteratorData = {
+var IteratorData = exports.IteratorData = {
   buffer: true,
   encodingLength: null,
   encode: null,
@@ -68,7 +68,7 @@ defineCallback()
 defineIteratorData()
 
 function defineGet () {
-  const enc = [
+  var enc = [
     encodings.varint,
     encodings.bytes
   ]
@@ -78,18 +78,20 @@ function defineGet () {
   Get.decode = decode
 
   function encodingLength (obj) {
-    let length = 0
+    var length = 0
     if (!defined(obj.id)) throw new Error("id is required")
-    length += 1 + enc[0].encodingLength(obj.id)
+    var len = enc[0].encodingLength(obj.id)
+    length += 1 + len
     if (!defined(obj.key)) throw new Error("key is required")
-    length += 1 + enc[1].encodingLength(obj.key)
+    var len = enc[1].encodingLength(obj.key)
+    length += 1 + len
     return length
   }
 
   function encode (obj, buf, offset) {
     if (!offset) offset = 0
     if (!buf) buf = Buffer.allocUnsafe(encodingLength(obj))
-    const oldOffset = offset
+    var oldOffset = offset
     if (!defined(obj.id)) throw new Error("id is required")
     buf[offset++] = 8
     enc[0].encode(obj.id, buf, offset)
@@ -106,22 +108,22 @@ function defineGet () {
     if (!offset) offset = 0
     if (!end) end = buf.length
     if (!(end <= buf.length && offset <= buf.length)) throw new Error("Decoded message is not valid")
-    const oldOffset = offset
-    const obj = {
+    var oldOffset = offset
+    var obj = {
       id: 0,
       key: null
     }
-    let found0 = false
-    let found1 = false
+    var found0 = false
+    var found1 = false
     while (true) {
       if (end <= offset) {
         if (!found0 || !found1) throw new Error("Decoded message is not valid")
         decode.bytes = offset - oldOffset
         return obj
       }
-      const prefix = varint.decode(buf, offset)
+      var prefix = varint.decode(buf, offset)
       offset += varint.decode.bytes
-      const tag = prefix >> 3
+      var tag = prefix >> 3
       switch (tag) {
         case 1:
         obj.id = enc[0].decode(buf, offset)
@@ -141,7 +143,7 @@ function defineGet () {
 }
 
 function definePut () {
-  const enc = [
+  var enc = [
     encodings.varint,
     encodings.bytes
   ]
@@ -151,13 +153,16 @@ function definePut () {
   Put.decode = decode
 
   function encodingLength (obj) {
-    let length = 0
+    var length = 0
     if (!defined(obj.id)) throw new Error("id is required")
-    length += 1 + enc[0].encodingLength(obj.id)
+    var len = enc[0].encodingLength(obj.id)
+    length += 1 + len
     if (!defined(obj.key)) throw new Error("key is required")
-    length += 1 + enc[1].encodingLength(obj.key)
+    var len = enc[1].encodingLength(obj.key)
+    length += 1 + len
     if (defined(obj.value)) {
-      length += 1 + enc[1].encodingLength(obj.value)
+      var len = enc[1].encodingLength(obj.value)
+      length += 1 + len
     }
     return length
   }
@@ -165,7 +170,7 @@ function definePut () {
   function encode (obj, buf, offset) {
     if (!offset) offset = 0
     if (!buf) buf = Buffer.allocUnsafe(encodingLength(obj))
-    const oldOffset = offset
+    var oldOffset = offset
     if (!defined(obj.id)) throw new Error("id is required")
     buf[offset++] = 8
     enc[0].encode(obj.id, buf, offset)
@@ -187,23 +192,23 @@ function definePut () {
     if (!offset) offset = 0
     if (!end) end = buf.length
     if (!(end <= buf.length && offset <= buf.length)) throw new Error("Decoded message is not valid")
-    const oldOffset = offset
-    const obj = {
+    var oldOffset = offset
+    var obj = {
       id: 0,
       key: null,
       value: null
     }
-    let found0 = false
-    let found1 = false
+    var found0 = false
+    var found1 = false
     while (true) {
       if (end <= offset) {
         if (!found0 || !found1) throw new Error("Decoded message is not valid")
         decode.bytes = offset - oldOffset
         return obj
       }
-      const prefix = varint.decode(buf, offset)
+      var prefix = varint.decode(buf, offset)
       offset += varint.decode.bytes
-      const tag = prefix >> 3
+      var tag = prefix >> 3
       switch (tag) {
         case 1:
         obj.id = enc[0].decode(buf, offset)
@@ -227,7 +232,7 @@ function definePut () {
 }
 
 function defineDelete () {
-  const enc = [
+  var enc = [
     encodings.varint,
     encodings.bytes
   ]
@@ -237,18 +242,20 @@ function defineDelete () {
   Delete.decode = decode
 
   function encodingLength (obj) {
-    let length = 0
+    var length = 0
     if (!defined(obj.id)) throw new Error("id is required")
-    length += 1 + enc[0].encodingLength(obj.id)
+    var len = enc[0].encodingLength(obj.id)
+    length += 1 + len
     if (!defined(obj.key)) throw new Error("key is required")
-    length += 1 + enc[1].encodingLength(obj.key)
+    var len = enc[1].encodingLength(obj.key)
+    length += 1 + len
     return length
   }
 
   function encode (obj, buf, offset) {
     if (!offset) offset = 0
     if (!buf) buf = Buffer.allocUnsafe(encodingLength(obj))
-    const oldOffset = offset
+    var oldOffset = offset
     if (!defined(obj.id)) throw new Error("id is required")
     buf[offset++] = 8
     enc[0].encode(obj.id, buf, offset)
@@ -265,22 +272,22 @@ function defineDelete () {
     if (!offset) offset = 0
     if (!end) end = buf.length
     if (!(end <= buf.length && offset <= buf.length)) throw new Error("Decoded message is not valid")
-    const oldOffset = offset
-    const obj = {
+    var oldOffset = offset
+    var obj = {
       id: 0,
       key: null
     }
-    let found0 = false
-    let found1 = false
+    var found0 = false
+    var found1 = false
     while (true) {
       if (end <= offset) {
         if (!found0 || !found1) throw new Error("Decoded message is not valid")
         decode.bytes = offset - oldOffset
         return obj
       }
-      const prefix = varint.decode(buf, offset)
+      var prefix = varint.decode(buf, offset)
       offset += varint.decode.bytes
-      const tag = prefix >> 3
+      var tag = prefix >> 3
       switch (tag) {
         case 1:
         obj.id = enc[0].decode(buf, offset)
@@ -300,7 +307,7 @@ function defineDelete () {
 }
 
 function defineBatch () {
-  const Operation = Batch.Operation = {
+  var Operation = Batch.Operation = {
     buffer: true,
     encodingLength: null,
     encode: null,
@@ -310,7 +317,7 @@ function defineBatch () {
   defineOperation()
 
   function defineOperation () {
-    const enc = [
+    var enc = [
       encodings.string,
       encodings.bytes
     ]
@@ -320,13 +327,16 @@ function defineBatch () {
     Operation.decode = decode
 
     function encodingLength (obj) {
-      let length = 0
+      var length = 0
       if (!defined(obj.type)) throw new Error("type is required")
-      length += 1 + enc[0].encodingLength(obj.type)
+      var len = enc[0].encodingLength(obj.type)
+      length += 1 + len
       if (!defined(obj.key)) throw new Error("key is required")
-      length += 1 + enc[1].encodingLength(obj.key)
+      var len = enc[1].encodingLength(obj.key)
+      length += 1 + len
       if (defined(obj.value)) {
-        length += 1 + enc[1].encodingLength(obj.value)
+        var len = enc[1].encodingLength(obj.value)
+        length += 1 + len
       }
       return length
     }
@@ -334,7 +344,7 @@ function defineBatch () {
     function encode (obj, buf, offset) {
       if (!offset) offset = 0
       if (!buf) buf = Buffer.allocUnsafe(encodingLength(obj))
-      const oldOffset = offset
+      var oldOffset = offset
       if (!defined(obj.type)) throw new Error("type is required")
       buf[offset++] = 10
       enc[0].encode(obj.type, buf, offset)
@@ -356,23 +366,23 @@ function defineBatch () {
       if (!offset) offset = 0
       if (!end) end = buf.length
       if (!(end <= buf.length && offset <= buf.length)) throw new Error("Decoded message is not valid")
-      const oldOffset = offset
-      const obj = {
+      var oldOffset = offset
+      var obj = {
         type: "",
         key: null,
         value: null
       }
-      let found0 = false
-      let found1 = false
+      var found0 = false
+      var found1 = false
       while (true) {
         if (end <= offset) {
           if (!found0 || !found1) throw new Error("Decoded message is not valid")
           decode.bytes = offset - oldOffset
           return obj
         }
-        const prefix = varint.decode(buf, offset)
+        var prefix = varint.decode(buf, offset)
         offset += varint.decode.bytes
-        const tag = prefix >> 3
+        var tag = prefix >> 3
         switch (tag) {
           case 1:
           obj.type = enc[0].decode(buf, offset)
@@ -395,7 +405,7 @@ function defineBatch () {
     }
   }
 
-  const enc = [
+  var enc = [
     encodings.varint,
     Operation
   ]
@@ -405,13 +415,14 @@ function defineBatch () {
   Batch.decode = decode
 
   function encodingLength (obj) {
-    let length = 0
+    var length = 0
     if (!defined(obj.id)) throw new Error("id is required")
-    length += 1 + enc[0].encodingLength(obj.id)
+    var len = enc[0].encodingLength(obj.id)
+    length += 1 + len
     if (defined(obj.ops)) {
-      for (let i = 0; i < obj.ops.length; i++) {
+      for (var i = 0; i < obj.ops.length; i++) {
         if (!defined(obj.ops[i])) continue
-        const len = enc[1].encodingLength(obj.ops[i])
+        var len = enc[1].encodingLength(obj.ops[i])
         length += varint.encodingLength(len)
         length += 1 + len
       }
@@ -422,13 +433,13 @@ function defineBatch () {
   function encode (obj, buf, offset) {
     if (!offset) offset = 0
     if (!buf) buf = Buffer.allocUnsafe(encodingLength(obj))
-    const oldOffset = offset
+    var oldOffset = offset
     if (!defined(obj.id)) throw new Error("id is required")
     buf[offset++] = 8
     enc[0].encode(obj.id, buf, offset)
     offset += enc[0].encode.bytes
     if (defined(obj.ops)) {
-      for (let i = 0; i < obj.ops.length; i++) {
+      for (var i = 0; i < obj.ops.length; i++) {
         if (!defined(obj.ops[i])) continue
         buf[offset++] = 18
         varint.encode(enc[1].encodingLength(obj.ops[i]), buf, offset)
@@ -445,21 +456,21 @@ function defineBatch () {
     if (!offset) offset = 0
     if (!end) end = buf.length
     if (!(end <= buf.length && offset <= buf.length)) throw new Error("Decoded message is not valid")
-    const oldOffset = offset
-    const obj = {
+    var oldOffset = offset
+    var obj = {
       id: 0,
       ops: []
     }
-    let found0 = false
+    var found0 = false
     while (true) {
       if (end <= offset) {
         if (!found0) throw new Error("Decoded message is not valid")
         decode.bytes = offset - oldOffset
         return obj
       }
-      const prefix = varint.decode(buf, offset)
+      var prefix = varint.decode(buf, offset)
       offset += varint.decode.bytes
-      const tag = prefix >> 3
+      var tag = prefix >> 3
       switch (tag) {
         case 1:
         obj.id = enc[0].decode(buf, offset)
@@ -467,8 +478,9 @@ function defineBatch () {
         found0 = true
         break
         case 2:
+        var len = varint.decode(buf, offset)
         offset += varint.decode.bytes
-        obj.ops.push(enc[1].decode(buf, offset, offset + varint.decode(buf, offset)))
+        obj.ops.push(enc[1].decode(buf, offset, offset + len))
         offset += enc[1].decode.bytes
         break
         default:
@@ -479,7 +491,7 @@ function defineBatch () {
 }
 
 function defineIterator () {
-  const Options = Iterator.Options = {
+  var Options = Iterator.Options = {
     buffer: true,
     encodingLength: null,
     encode: null,
@@ -489,7 +501,7 @@ function defineIterator () {
   defineOptions()
 
   function defineOptions () {
-    const enc = [
+    var enc = [
       encodings.bool,
       encodings.bytes,
       encodings.sint64
@@ -500,30 +512,38 @@ function defineIterator () {
     Options.decode = decode
 
     function encodingLength (obj) {
-      let length = 0
+      var length = 0
       if (defined(obj.keys)) {
-        length += 1 + enc[0].encodingLength(obj.keys)
+        var len = enc[0].encodingLength(obj.keys)
+        length += 1 + len
       }
       if (defined(obj.values)) {
-        length += 1 + enc[0].encodingLength(obj.values)
+        var len = enc[0].encodingLength(obj.values)
+        length += 1 + len
       }
       if (defined(obj.gt)) {
-        length += 1 + enc[1].encodingLength(obj.gt)
+        var len = enc[1].encodingLength(obj.gt)
+        length += 1 + len
       }
       if (defined(obj.gte)) {
-        length += 1 + enc[1].encodingLength(obj.gte)
+        var len = enc[1].encodingLength(obj.gte)
+        length += 1 + len
       }
       if (defined(obj.lt)) {
-        length += 1 + enc[1].encodingLength(obj.lt)
+        var len = enc[1].encodingLength(obj.lt)
+        length += 1 + len
       }
       if (defined(obj.lte)) {
-        length += 1 + enc[1].encodingLength(obj.lte)
+        var len = enc[1].encodingLength(obj.lte)
+        length += 1 + len
       }
       if (defined(obj.limit)) {
-        length += 1 + enc[2].encodingLength(obj.limit)
+        var len = enc[2].encodingLength(obj.limit)
+        length += 1 + len
       }
       if (defined(obj.reverse)) {
-        length += 1 + enc[0].encodingLength(obj.reverse)
+        var len = enc[0].encodingLength(obj.reverse)
+        length += 1 + len
       }
       return length
     }
@@ -531,7 +551,7 @@ function defineIterator () {
     function encode (obj, buf, offset) {
       if (!offset) offset = 0
       if (!buf) buf = Buffer.allocUnsafe(encodingLength(obj))
-      const oldOffset = offset
+      var oldOffset = offset
       if (defined(obj.keys)) {
         buf[offset++] = 8
         enc[0].encode(obj.keys, buf, offset)
@@ -580,8 +600,8 @@ function defineIterator () {
       if (!offset) offset = 0
       if (!end) end = buf.length
       if (!(end <= buf.length && offset <= buf.length)) throw new Error("Decoded message is not valid")
-      const oldOffset = offset
-      const obj = {
+      var oldOffset = offset
+      var obj = {
         keys: false,
         values: false,
         gt: null,
@@ -596,9 +616,9 @@ function defineIterator () {
           decode.bytes = offset - oldOffset
           return obj
         }
-        const prefix = varint.decode(buf, offset)
+        var prefix = varint.decode(buf, offset)
         offset += varint.decode.bytes
-        const tag = prefix >> 3
+        var tag = prefix >> 3
         switch (tag) {
           case 1:
           obj.keys = enc[0].decode(buf, offset)
@@ -639,7 +659,7 @@ function defineIterator () {
     }
   }
 
-  const enc = [
+  var enc = [
     encodings.varint,
     Options
   ]
@@ -649,14 +669,16 @@ function defineIterator () {
   Iterator.decode = decode
 
   function encodingLength (obj) {
-    let length = 0
+    var length = 0
     if (!defined(obj.id)) throw new Error("id is required")
-    length += 1 + enc[0].encodingLength(obj.id)
+    var len = enc[0].encodingLength(obj.id)
+    length += 1 + len
     if (defined(obj.batch)) {
-      length += 1 + enc[0].encodingLength(obj.batch)
+      var len = enc[0].encodingLength(obj.batch)
+      length += 1 + len
     }
     if (defined(obj.options)) {
-      const len = enc[1].encodingLength(obj.options)
+      var len = enc[1].encodingLength(obj.options)
       length += varint.encodingLength(len)
       length += 1 + len
     }
@@ -666,7 +688,7 @@ function defineIterator () {
   function encode (obj, buf, offset) {
     if (!offset) offset = 0
     if (!buf) buf = Buffer.allocUnsafe(encodingLength(obj))
-    const oldOffset = offset
+    var oldOffset = offset
     if (!defined(obj.id)) throw new Error("id is required")
     buf[offset++] = 8
     enc[0].encode(obj.id, buf, offset)
@@ -691,22 +713,22 @@ function defineIterator () {
     if (!offset) offset = 0
     if (!end) end = buf.length
     if (!(end <= buf.length && offset <= buf.length)) throw new Error("Decoded message is not valid")
-    const oldOffset = offset
-    const obj = {
+    var oldOffset = offset
+    var obj = {
       id: 0,
       batch: 0,
       options: null
     }
-    let found0 = false
+    var found0 = false
     while (true) {
       if (end <= offset) {
         if (!found0) throw new Error("Decoded message is not valid")
         decode.bytes = offset - oldOffset
         return obj
       }
-      const prefix = varint.decode(buf, offset)
+      var prefix = varint.decode(buf, offset)
       offset += varint.decode.bytes
-      const tag = prefix >> 3
+      var tag = prefix >> 3
       switch (tag) {
         case 1:
         obj.id = enc[0].decode(buf, offset)
@@ -718,8 +740,9 @@ function defineIterator () {
         offset += enc[0].decode.bytes
         break
         case 3:
+        var len = varint.decode(buf, offset)
         offset += varint.decode.bytes
-        obj.options = enc[1].decode(buf, offset, offset + varint.decode(buf, offset))
+        obj.options = enc[1].decode(buf, offset, offset + len)
         offset += enc[1].decode.bytes
         break
         default:
@@ -730,7 +753,7 @@ function defineIterator () {
 }
 
 function defineCallback () {
-  const enc = [
+  var enc = [
     encodings.varint,
     encodings.string,
     encodings.bytes
@@ -741,14 +764,17 @@ function defineCallback () {
   Callback.decode = decode
 
   function encodingLength (obj) {
-    let length = 0
+    var length = 0
     if (!defined(obj.id)) throw new Error("id is required")
-    length += 1 + enc[0].encodingLength(obj.id)
+    var len = enc[0].encodingLength(obj.id)
+    length += 1 + len
     if (defined(obj.error)) {
-      length += 1 + enc[1].encodingLength(obj.error)
+      var len = enc[1].encodingLength(obj.error)
+      length += 1 + len
     }
     if (defined(obj.value)) {
-      length += 1 + enc[2].encodingLength(obj.value)
+      var len = enc[2].encodingLength(obj.value)
+      length += 1 + len
     }
     return length
   }
@@ -756,7 +782,7 @@ function defineCallback () {
   function encode (obj, buf, offset) {
     if (!offset) offset = 0
     if (!buf) buf = Buffer.allocUnsafe(encodingLength(obj))
-    const oldOffset = offset
+    var oldOffset = offset
     if (!defined(obj.id)) throw new Error("id is required")
     buf[offset++] = 8
     enc[0].encode(obj.id, buf, offset)
@@ -779,22 +805,22 @@ function defineCallback () {
     if (!offset) offset = 0
     if (!end) end = buf.length
     if (!(end <= buf.length && offset <= buf.length)) throw new Error("Decoded message is not valid")
-    const oldOffset = offset
-    const obj = {
+    var oldOffset = offset
+    var obj = {
       id: 0,
       error: "",
       value: null
     }
-    let found0 = false
+    var found0 = false
     while (true) {
       if (end <= offset) {
         if (!found0) throw new Error("Decoded message is not valid")
         decode.bytes = offset - oldOffset
         return obj
       }
-      const prefix = varint.decode(buf, offset)
+      var prefix = varint.decode(buf, offset)
       offset += varint.decode.bytes
-      const tag = prefix >> 3
+      var tag = prefix >> 3
       switch (tag) {
         case 1:
         obj.id = enc[0].decode(buf, offset)
@@ -817,7 +843,7 @@ function defineCallback () {
 }
 
 function defineIteratorData () {
-  const enc = [
+  var enc = [
     encodings.varint,
     encodings.string,
     encodings.bytes
@@ -828,17 +854,21 @@ function defineIteratorData () {
   IteratorData.decode = decode
 
   function encodingLength (obj) {
-    let length = 0
+    var length = 0
     if (!defined(obj.id)) throw new Error("id is required")
-    length += 1 + enc[0].encodingLength(obj.id)
+    var len = enc[0].encodingLength(obj.id)
+    length += 1 + len
     if (defined(obj.error)) {
-      length += 1 + enc[1].encodingLength(obj.error)
+      var len = enc[1].encodingLength(obj.error)
+      length += 1 + len
     }
     if (defined(obj.key)) {
-      length += 1 + enc[2].encodingLength(obj.key)
+      var len = enc[2].encodingLength(obj.key)
+      length += 1 + len
     }
     if (defined(obj.value)) {
-      length += 1 + enc[2].encodingLength(obj.value)
+      var len = enc[2].encodingLength(obj.value)
+      length += 1 + len
     }
     return length
   }
@@ -846,7 +876,7 @@ function defineIteratorData () {
   function encode (obj, buf, offset) {
     if (!offset) offset = 0
     if (!buf) buf = Buffer.allocUnsafe(encodingLength(obj))
-    const oldOffset = offset
+    var oldOffset = offset
     if (!defined(obj.id)) throw new Error("id is required")
     buf[offset++] = 8
     enc[0].encode(obj.id, buf, offset)
@@ -874,23 +904,23 @@ function defineIteratorData () {
     if (!offset) offset = 0
     if (!end) end = buf.length
     if (!(end <= buf.length && offset <= buf.length)) throw new Error("Decoded message is not valid")
-    const oldOffset = offset
-    const obj = {
+    var oldOffset = offset
+    var obj = {
       id: 0,
       error: "",
       key: null,
       value: null
     }
-    let found0 = false
+    var found0 = false
     while (true) {
       if (end <= offset) {
         if (!found0) throw new Error("Decoded message is not valid")
         decode.bytes = offset - oldOffset
         return obj
       }
-      const prefix = varint.decode(buf, offset)
+      var prefix = varint.decode(buf, offset)
       offset += varint.decode.bytes
-      const tag = prefix >> 3
+      var tag = prefix >> 3
       switch (tag) {
         case 1:
         obj.id = enc[0].decode(buf, offset)
diff --git a/package.json b/package.json
index abc5e4e..acc105f 100644
--- a/package.json
+++ b/package.json
@@ -52,6 +52,11 @@
   },
   "homepage": "https://github.com/Level/multileveldown",
   "engines": {
-    "node": ">=8"
+    "node": ">=10"
+  },
+  "standard": {
+    "ignore": [
+      "messages.js"
+    ]
   }
 }