events: add/removeListener should call on/off

doc/api/events.md

@@ -290,8 +290,10 @@ added: v0.1.26
 -->
 * `eventName` {string|symbol}
 * `listener` {Function}
+* Returns: {EventEmitter}
 
-Alias for `emitter.on(eventName, listener)`.
+This function is implemented by calling [`emitter.on()`][].
+When overriding, override [`emitter.on()`][].
 
 ### emitter.emit(eventName[, ...args])
 <!-- YAML
@@ -415,7 +417,86 @@ added: v10.0.0
 * `listener` {Function}
 * Returns: {EventEmitter}
 
-Alias for [`emitter.removeListener()`][].
+Removes the specified `listener` from the listener array for the event named
+`eventName`.
+
+```js
+const callback = (stream) => {
+  console.log('someone connected!');
+};
+server.on('connection', callback);
+// ...
+server.off('connection', callback);
+```
+
+`off()` will remove, at most, one instance of a listener from the
+listener array. If any single listener has been added multiple times to the
+listener array for the specified `eventName`, then `off()` must be
+called multiple times to remove each instance.
+
+Once an event has been emitted, all listeners attached to it at the
+time of emitting will be called in order. This implies that any
+`off()` or `removeAllListeners()` calls *after* emitting and
+*before* the last listener finishes execution will not remove them from
+`emit()` in progress. Subsequent events will behave as expected.
+
+```js
+const myEmitter = new MyEmitter();
+
+const callbackA = () => {
+  console.log('A');
+  myEmitter.off('event', callbackB);
+};
+
+const callbackB = () => {
+  console.log('B');
+};
+
+myEmitter.on('event', callbackA);
+
+myEmitter.on('event', callbackB);
+
+// callbackA removes listener callbackB but it will still be called.
+// Internal listener array at time of emit [callbackA, callbackB]
+myEmitter.emit('event');
+// Prints:
+//   A
+//   B
+
+// callbackB is now removed.
+// Internal listener array [callbackA]
+myEmitter.emit('event');
+// Prints:
+//   A
+```
+
+Because listeners are managed using an internal array, calling this will
+change the position indices of any listener registered *after* the listener
+being removed. This will not impact the order in which listeners are called,
+but it means that any copies of the listener array as returned by
+the `emitter.listeners()` method will need to be recreated.
+
+When a single function has been added as a handler multiple times for a single
+event (as in the example below), `off()` will remove the most
+recently added instance. In the example the `once('ping')`
+listener is removed:
+
+```js
+const ee = new EventEmitter();
+
+function pong() {
+  console.log('pong');
+}
+
+ee.on('ping', pong);
+ee.once('ping', pong);
+ee.off('ping', pong);
+
+ee.emit('ping');
+ee.emit('ping');
+```
+
+Returns a reference to the `EventEmitter`, so that calls can be chained.
 
 ### emitter.on(eventName, listener)
 <!-- YAML
@@ -555,86 +636,8 @@ added: v0.1.26
 * `listener` {Function}
 * Returns: {EventEmitter}
 
-Removes the specified `listener` from the listener array for the event named
-`eventName`.
-
-```js
-const callback = (stream) => {
-  console.log('someone connected!');
-};
-server.on('connection', callback);
-// ...
-server.removeListener('connection', callback);
-```
-
-`removeListener()` will remove, at most, one instance of a listener from the
-listener array. If any single listener has been added multiple times to the
-listener array for the specified `eventName`, then `removeListener()` must be
-called multiple times to remove each instance.
-
-Once an event has been emitted, all listeners attached to it at the
-time of emitting will be called in order. This implies that any
-`removeListener()` or `removeAllListeners()` calls *after* emitting and
-*before* the last listener finishes execution will not remove them from
-`emit()` in progress. Subsequent events will behave as expected.
-
-```js
-const myEmitter = new MyEmitter();
-
-const callbackA = () => {
-  console.log('A');
-  myEmitter.removeListener('event', callbackB);
-};
-
-const callbackB = () => {
-  console.log('B');
-};
-
-myEmitter.on('event', callbackA);
-
-myEmitter.on('event', callbackB);
-
-// callbackA removes listener callbackB but it will still be called.
-// Internal listener array at time of emit [callbackA, callbackB]
-myEmitter.emit('event');
-// Prints:
-//   A
-//   B
-
-// callbackB is now removed.
-// Internal listener array [callbackA]
-myEmitter.emit('event');
-// Prints:
-//   A
-```
-
-Because listeners are managed using an internal array, calling this will
-change the position indices of any listener registered *after* the listener
-being removed. This will not impact the order in which listeners are called,
-but it means that any copies of the listener array as returned by
-the `emitter.listeners()` method will need to be recreated.
-
-When a single function has been added as a handler multiple times for a single
-event (as in the example below), `removeListener()` will remove the most
-recently added instance. In the example the `once('ping')`
-listener is removed:
-
-```js
-const ee = new EventEmitter();
-
-function pong() {
-  console.log('pong');
-}
-
-ee.on('ping', pong);
-ee.once('ping', pong);
-ee.removeListener('ping', pong);
-
-ee.emit('ping');
-ee.emit('ping');
-```
-
-Returns a reference to the `EventEmitter`, so that calls can be chained.
+This function is implemented by calling [`emitter.off()`][].
+When overriding, override [`emitter.off()`][].
 
 ### emitter.setMaxListeners(n)
 <!-- YAML
@@ -731,7 +734,8 @@ run();
 [`EventEmitter.defaultMaxListeners`]: #events_eventemitter_defaultmaxlisteners
 [`domain`]: domain.html
 [`emitter.listenerCount()`]: #events_emitter_listenercount_eventname
-[`emitter.removeListener()`]: #events_emitter_removelistener_eventname_listener
+[`emitter.on()`]: #events_emitter_on_eventname_listener
+[`emitter.off()`]: #events_emitter_off_eventname_listener
 [`emitter.setMaxListeners(n)`]: #events_emitter_setmaxlisteners_n
 [`fs.ReadStream`]: fs.html#fs_class_fs_readstream
 [`net.Server`]: net.html#net_class_net_server

lib/_http_server.js

@@ -421,7 +421,6 @@ function connectionListenerInternal(server, socket) {
 
   // Overrides to unconsume on `data`, `readable` listeners
   socket.on = generateSocketListenerWrapper('on');
-  socket.addListener = generateSocketListenerWrapper('addListener');
   socket.prependListener = generateSocketListenerWrapper('prependListener');
 
   // We only consume the socket if it has never been consumed before.
@@ -792,7 +791,6 @@ function generateSocketListenerWrapper(originalFnName) {
     const res = net.Socket.prototype[originalFnName].call(this, ev, fn);
     if (!this.parser) {
       this.on = net.Socket.prototype.on;
-      this.addListener = net.Socket.prototype.addListener;
       this.prependListener = net.Socket.prototype.prependListener;
       return res;
     }

lib/_stream_readable.js

@@ -897,10 +897,9 @@ Readable.prototype.on = function(ev, fn) {
 
   return res;
 };
-Readable.prototype.addListener = Readable.prototype.on;
 
-Readable.prototype.removeListener = function(ev, fn) {
-  const res = Stream.prototype.removeListener.call(this, ev, fn);
+Readable.prototype.off = function(ev, fn) {
+  const res = Stream.prototype.off.call(this, ev, fn);
 
   if (ev === 'readable') {
     // We need to check if there is someone still listening to

lib/events.js

@@ -280,10 +280,12 @@ function _addListener(target, type, listener, prepend) {
 }
 
 EventEmitter.prototype.addListener = function addListener(type, listener) {
-  return _addListener(this, type, listener, false);
+  return this.on(type, listener);
 };
 
-EventEmitter.prototype.on = EventEmitter.prototype.addListener;
+EventEmitter.prototype.on = function on(type, listener) {
+  return _addListener(this, type, listener, false);
+};
 
 EventEmitter.prototype.prependListener =
     function prependListener(type, listener) {
@@ -324,8 +326,8 @@ EventEmitter.prototype.prependOnceListener =
     };
 
 // Emits a 'removeListener' event if and only if the listener was removed.
-EventEmitter.prototype.removeListener =
-    function removeListener(type, listener) {
+EventEmitter.prototype.off =
+    function off(type, listener) {
       let originalListener;
 
       checkListener(listener);
@@ -378,7 +380,10 @@ EventEmitter.prototype.removeListener =
       return this;
     };
 
-EventEmitter.prototype.off = EventEmitter.prototype.removeListener;
+EventEmitter.prototype.removeListener =
+    function removeListener(type, listener) {
+      return this.off(type, listener);
+    };
 
 EventEmitter.prototype.removeAllListeners =
     function removeAllListeners(type) {

test/parallel/test-event-emitter-add-listeners.js

@@ -29,9 +29,6 @@ const EventEmitter = require('events');
   const events_new_listener_emitted = [];
   const listeners_new_listener_emitted = [];
 
-  // Sanity check
-  assert.strictEqual(ee.addListener, ee.on);
-
   ee.on('newListener', function(event, listener) {
     // Don't track newListener listeners.
     if (event === 'newListener')

test/parallel/test-event-emitter-method-names.js

@@ -26,10 +26,9 @@ const events = require('events');
 
 const E = events.EventEmitter.prototype;
 assert.strictEqual(E.constructor.name, 'EventEmitter');
-assert.strictEqual(E.on, E.addListener);  // Same method.
-assert.strictEqual(E.off, E.removeListener);  // Same method.
+
 Object.getOwnPropertyNames(E).forEach(function(name) {
-  if (name === 'constructor' || name === 'on' || name === 'off') return;
+  if (name === 'constructor') return;
   if (typeof E[name] !== 'function') return;
   assert.strictEqual(E[name].name, name);
 });

test/parallel/test-events-override.js

@@ -0,0 +1,16 @@
+'use strict';
+
+const common = require('../common');
+const { EventEmitter: EE } = require('events');
+
+{
+  const e = new EE();
+  e.on = common.mustCall();
+  e.addListener('test', () => {});
+}
+
+{
+  const e = new EE();
+  e.off = common.mustCall();
+  e.removeListener('test', () => {});
+}