Use arrow functions where this is needed

abstract-iterator.js

@@ -13,29 +13,27 @@ function AbstractIterator (db) {
 }
 
 AbstractIterator.prototype.next = function (callback) {
-  const self = this
-
   if (typeof callback !== 'function') {
     throw new Error('next() requires a callback argument')
   }
 
-  if (self._ended) {
+  if (this._ended) {
     nextTick(callback, new Error('cannot call next() after end()'))
-    return self
+    return this
   }
 
-  if (self._nexting) {
+  if (this._nexting) {
     nextTick(callback, new Error('cannot call next() before previous next() has completed'))
-    return self
+    return this
   }
 
-  self._nexting = true
-  self._next(function () {
-    self._nexting = false
-    callback.apply(null, arguments)
+  this._nexting = true
+  this._next((err, ...rest) => {
+    this._nexting = false
+    callback(err, ...rest)
   })
 
-  return self
+  return this
 }
 
 AbstractIterator.prototype._next = function (callback) {

abstract-leveldown.js

@@ -18,7 +18,6 @@ function AbstractLevelDOWN (manifest) {
 }
 
 AbstractLevelDOWN.prototype.open = function (options, callback) {
-  const self = this
   const oldStatus = this.status
 
   if (typeof options === 'function') callback = options
@@ -33,12 +32,12 @@ AbstractLevelDOWN.prototype.open = function (options, callback) {
   options.errorIfExists = !!options.errorIfExists
 
   this.status = 'opening'
-  this._open(options, function (err) {
+  this._open(options, (err) => {
     if (err) {
-      self.status = oldStatus
+      this.status = oldStatus
       return callback(err)
     }
-    self.status = 'open'
+    this.status = 'open'
     callback()
   })
 }
@@ -48,20 +47,19 @@ AbstractLevelDOWN.prototype._open = function (options, callback) {
 }
 
 AbstractLevelDOWN.prototype.close = function (callback) {
-  const self = this
   const oldStatus = this.status
 
   if (typeof callback !== 'function') {
     throw new Error('close() requires a callback argument')
   }
 
   this.status = 'closing'
-  this._close(function (err) {
+  this._close((err) => {
     if (err) {
-      self.status = oldStatus
+      this.status = oldStatus
       return callback(err)
     }
-    self.status = 'closed'
+    this.status = 'closed'
     callback()
   })
 }