events: deprecate static listenerCount function

thefourtheye · rvagg · commit 3e6a6fcdd6be · 2015-08-20T20:49:36.000+10:00
As per the discussion in #734, this patch deprecates the usage of `EventEmitter.listenerCount` static function in the docs, and introduces the `listenerCount` function in the prototype of `EventEmitter` itself. PR-URL: #2349 Reviewed-By: Trevor Norris <trev.norris@gmail.com> Reviewed-By: Brian White <mscdex@mscdex.net>
diff --git a/benchmark/events/ee-listener-count-on-prototype.js b/benchmark/events/ee-listener-count-on-prototype.js
@@ -7,14 +7,13 @@ function main(conf) {
 var n = conf.n | 0;
 
 var ee = new EventEmitter();
- var listenerCount = EventEmitter.listenerCount;
 
 for (var k = 0; k < 10; k += 1)
 ee.on('dummy', function() {});
 
 bench.start();
 for (var i = 0; i < n; i += 1) {
- var r = listenerCount(ee, 'dummy');
+ var r = ee.listenerCount('dummy');
 }
 bench.end(n);
 }
diff --git a/doc/api/events.markdown b/doc/api/events.markdown
@@ -137,10 +137,17 @@ Execute each of the listeners in order with the supplied arguments.
 Returns `true` if event had listeners, `false` otherwise.
 
 
+### emitter.listenerCount(type)
+
+* `type` {Value} The type of event
+
+Returns the number of listeners listening to the `type` of event.
+
 ### Class Method: EventEmitter.listenerCount(emitter, event)
 
 Return the number of listeners for a given event.
 
+_Note: This is deprecated. Use `emitter.listenerCount` instead._
 
 ### Event: 'newListener'
 
diff --git a/lib/_http_client.js b/lib/_http_client.js
@@ -322,7 +322,7 @@ function socketOnData(d) {
 var bodyHead = d.slice(bytesParsed, d.length);
 
 var eventName = req.method === 'CONNECT' ? 'connect' : 'upgrade';
- if (EventEmitter.listenerCount(req, eventName) > 0) {
+ if (req.listenerCount(eventName) > 0) {
 req.upgradeOrConnect = true;
 
 // detach the socket
diff --git a/lib/_http_server.js b/lib/_http_server.js
@@ -343,7 +343,7 @@ function connectionListener(socket) {
 parser = null;
 
 var eventName = req.method === 'CONNECT' ? 'connect' : 'upgrade';
- if (EventEmitter.listenerCount(self, eventName) > 0) {
+ if (self.listenerCount(eventName) > 0) {
 debug('SERVER have listener for %s', eventName);
 var bodyHead = d.slice(bytesParsed, d.length);
 
@@ -467,7 +467,7 @@ function connectionListener(socket) {
 (req.httpVersionMajor == 1 && req.httpVersionMinor == 1) &&
 continueExpression.test(req.headers['expect'])) {
 res._expect_continue = true;
- if (EventEmitter.listenerCount(self, 'checkContinue') > 0) {
+ if (self.listenerCount('checkContinue') > 0) {
 self.emit('checkContinue', req, res);
 } else {
 res.writeContinue();
diff --git a/lib/_stream_readable.js b/lib/_stream_readable.js
@@ -533,7 +533,7 @@ Readable.prototype.pipe = function(dest, pipeOpts) {
 debug('onerror', er);
 unpipe();
 dest.removeListener('error', onerror);
- if (EE.listenerCount(dest, 'error') === 0)
+ if (dest.listenerCount('error') === 0)
 dest.emit('error', er);
 }
 // This is a brutally ugly hack to make sure that our error handler
@@ -582,7 +582,7 @@ function pipeOnDrain(src) {
 debug('pipeOnDrain', state.awaitDrain);
 if (state.awaitDrain)
 state.awaitDrain--;
- if (state.awaitDrain === 0 && EE.listenerCount(src, 'data')) {
+ if (state.awaitDrain === 0 && src.listenerCount('data')) {
 state.flowing = true;
 flow(src);
 }
diff --git a/lib/_tls_wrap.js b/lib/_tls_wrap.js
@@ -5,7 +5,6 @@ const crypto = require('crypto');
 const net = require('net');
 const tls = require('tls');
 const util = require('util');
-const listenerCount = require('events').listenerCount;
 const common = require('_tls_common');
 const StreamWrap = require('_stream_wrap').StreamWrap;
 const Buffer = require('buffer').Buffer;
@@ -116,7 +115,7 @@ function requestOCSP(self, hello, ctx, cb) {
 if (ctx.context)
 ctx = ctx.context;
 
- if (listenerCount(self.server, 'OCSPRequest') === 0) {
+ if (self.server.listenerCount('OCSPRequest') === 0) {
 return cb(null);
 } else {
 self.server.emit('OCSPRequest',
@@ -396,11 +395,11 @@ TLSSocket.prototype._init = function(socket, wrap) {
 ssl.handshakes = 0;
 
 if (this.server) {
- if (listenerCount(this.server, 'resumeSession') > 0 ||
- listenerCount(this.server, 'newSession') > 0) {
+ if (this.server.listenerCount('resumeSession') > 0 ||
+ this.server.listenerCount('newSession') > 0) {
 ssl.enableSessionCallbacks();
 }
- if (listenerCount(this.server, 'OCSPRequest') > 0)
+ if (this.server.listenerCount('OCSPRequest') > 0)
 ssl.enableCertCb();
 }
 } else {
diff --git a/lib/events.js b/lib/events.js
@@ -395,19 +395,23 @@ EventEmitter.prototype.listeners = function listeners(type) {
 };
 
 EventEmitter.listenerCount = function(emitter, type) {
- var evlistener;
- var ret = 0;
- var events = emitter._events;
+ return emitter.listenerCount(type);
+};
+
+EventEmitter.prototype.listenerCount = function listenerCount(type) {
+ const events = this._events;
 
 if (events) {
- evlistener = events[type];
- if (typeof evlistener === 'function')
- ret = 1;
- else if (evlistener)
- ret = evlistener.length;
+ const evlistener = events[type];
+
+ if (typeof evlistener === 'function') {
+ return 1;
+ } else if (evlistener) {
+ return evlistener.length;
+ }
 }
 
- return ret;
+ return 0;
 };
 
 // About 1.5x faster than the two-arg version of Array#splice().
diff --git a/lib/fs.js b/lib/fs.js
@@ -1354,7 +1354,7 @@ fs.unwatchFile = function(filename, listener) {
 stat.removeAllListeners('change');
 }
 
- if (EventEmitter.listenerCount(stat, 'change') === 0) {
+ if (stat.listenerCount('change') === 0) {
 stat.stop();
 statWatchers.delete(filename);
 }
diff --git a/lib/readline.js b/lib/readline.js
@@ -683,7 +683,7 @@ Interface.prototype._ttyWrite = function(s, key) {
 
 switch (key.name) {
 case 'c':
- if (EventEmitter.listenerCount(this, 'SIGINT') > 0) {
+ if (this.listenerCount('SIGINT') > 0) {
 this.emit('SIGINT');
 } else {
 // This readline instance is finished
@@ -746,7 +746,7 @@ Interface.prototype._ttyWrite = function(s, key) {
 
 case 'z':
 if (process.platform == 'win32') break;
- if (EventEmitter.listenerCount(this, 'SIGTSTP') > 0) {
+ if (this.listenerCount('SIGTSTP') > 0) {
 this.emit('SIGTSTP');
 } else {
 process.once('SIGCONT', (function(self) {
@@ -907,7 +907,7 @@ function emitKeypressEvents(stream) {
 stream[ESCAPE_DECODER].next();
 
 function onData(b) {
- if (EventEmitter.listenerCount(stream, 'keypress') > 0) {
+ if (stream.listenerCount('keypress') > 0) {
 var r = stream[KEYPRESS_DECODER].write(b);
 if (r) {
 for (var i = 0; i < r.length; i++) {
@@ -936,7 +936,7 @@ function emitKeypressEvents(stream) {
 }
 }
 
- if (EventEmitter.listenerCount(stream, 'keypress') > 0) {
+ if (stream.listenerCount('keypress') > 0) {
 stream.on('data', onData);
 } else {
 stream.on('newListener', onNewListener);
diff --git a/lib/stream.js b/lib/stream.js
@@ -70,7 +70,7 @@ Stream.prototype.pipe = function(dest, options) {
 // don't leave dangling pipes when there are errors.
 function onerror(er) {
 cleanup();
- if (EE.listenerCount(this, 'error') === 0) {
+ if (this.listenerCount('error') === 0) {
 throw er; // Unhandled stream error in pipe.
 }
 }
diff --git a/src/node.js b/src/node.js
@@ -802,8 +802,7 @@
 });
 
 process.on('removeListener', function(type, listener) {
- if (signalWraps.hasOwnProperty(type) &&
- NativeModule.require('events').listenerCount(this, type) === 0) {
+ if (signalWraps.hasOwnProperty(type) && this.listenerCount(type) === 0) {
 signalWraps[type].close();
 delete signalWraps[type];
 }
diff --git a/test/parallel/test-event-emitter-listener-count.js b/test/parallel/test-event-emitter-listener-count.js
@@ -0,0 +1,18 @@
+'use strict';
+
+const common = require('../common');
+const assert = require('assert');
+const EventEmitter = require('events');
+
+const emitter = new EventEmitter();
+emitter.on('foo', function() {});
+emitter.on('foo', function() {});
+emitter.on('baz', function() {});
+// Allow any type
+emitter.on(123, function() {});
+
+assert.strictEqual(EventEmitter.listenerCount(emitter, 'foo'), 2);
+assert.strictEqual(emitter.listenerCount('foo'), 2);
+assert.strictEqual(emitter.listenerCount('bar'), 0);
+assert.strictEqual(emitter.listenerCount('baz'), 1);
+assert.strictEqual(emitter.listenerCount(123), 1);
diff --git a/test/parallel/test-event-emitter-subclass.js b/test/parallel/test-event-emitter-subclass.js
@@ -46,4 +46,4 @@ var ee2 = new MyEE2();
 
 ee1.on('x', function() {});
 
-assert.equal(EventEmitter.listenerCount(ee2, 'x'), 0);
+assert.equal(ee2.listenerCount('x'), 0);

Original file line number	Diff line number	Diff line change
`@@ -7,14 +7,13 @@ function main(conf) {`
`7`	`7`	`varn=conf.n\|0;`
`8`	`8`
`9`	`9`	`varee=newEventEmitter();`
`10`		`-varlistenerCount=EventEmitter.listenerCount;`
`11`	`10`
`12`	`11`	`for(vark=0;k<10;k+=1)`
`13`	`12`	`ee.on('dummy',function(){});`
`14`	`13`
`15`	`14`	`bench.start();`
`16`	`15`	`for(vari=0;i<n;i+=1){`
`17`		`-varr=listenerCount(ee,'dummy');`
	`16`	`+varr=ee.listenerCount('dummy');`
`18`	`17`	`}`
`19`	`18`	`bench.end(n);`
`20`	`19`	`}`
-Original file line number
+Diff line change
 varbodyHead=d.slice(bytesParsed,d.length);
 vareventName=req.method==='CONNECT' ? 'connect' : 'upgrade';
 -if(EventEmitter.listenerCount(req,eventName)>0){
 +if(req.listenerCount(eventName)>0){
 req.upgradeOrConnect=true;
 // detach the socket
-Original file line number
+Diff line change
 parser=null;
 vareventName=req.method==='CONNECT' ? 'connect' : 'upgrade';
 -if(EventEmitter.listenerCount(self,eventName)>0){
 +if(self.listenerCount(eventName)>0){
 debug('SERVER have listener for %s',eventName);
 varbodyHead=d.slice(bytesParsed,d.length);
 (req.httpVersionMajor==1&&req.httpVersionMinor==1)&&
 continueExpression.test(req.headers['expect'])){
 res._expect_continue=true;
 -if(EventEmitter.listenerCount(self,'checkContinue')>0){
 +if(self.listenerCount('checkContinue')>0){
 self.emit('checkContinue',req,res);
 }else{
 res.writeContinue();
-Original file line number
+Diff line change
 debug('onerror',er);
 unpipe();
 dest.removeListener('error',onerror);
 -if(EE.listenerCount(dest,'error')===0)
 +if(dest.listenerCount('error')===0)
 dest.emit('error',er);
+}
 // This is a brutally ugly hack to make sure that our error handler
 debug('pipeOnDrain',state.awaitDrain);
 if(state.awaitDrain)
 state.awaitDrain--;
 -if(state.awaitDrain===0&&EE.listenerCount(src,'data')){
 +if(state.awaitDrain===0&&src.listenerCount('data')){
 state.flowing=true;
 flow(src);
+}
-Original file line number
+Diff line change
 constnet=require('net');
 consttls=require('tls');
 constutil=require('util');
 -constlistenerCount=require('events').listenerCount;
 constcommon=require('_tls_common');
 constStreamWrap=require('_stream_wrap').StreamWrap;
 constBuffer=require('buffer').Buffer;
 if(ctx.context)
 ctx=ctx.context;
 -if(listenerCount(self.server,'OCSPRequest')===0){
 +if(self.server.listenerCount('OCSPRequest')===0){
 returncb(null);
 }else{
 self.server.emit('OCSPRequest',
 ssl.handshakes=0;
 if(this.server){
 -if(listenerCount(this.server,'resumeSession')>0||
 -listenerCount(this.server,'newSession')>0){
 +if(this.server.listenerCount('resumeSession')>0||
 +this.server.listenerCount('newSession')>0){
 ssl.enableSessionCallbacks();
+}
 -if(listenerCount(this.server,'OCSPRequest')>0)
 +if(this.server.listenerCount('OCSPRequest')>0)
 ssl.enableCertCb();
+}
 }else{
-Original file line number
+Diff line change
 };
 EventEmitter.listenerCount=function(emitter,type){
 -varevlistener;
 -varret=0;
 -varevents=emitter._events;
 +returnemitter.listenerCount(type);
 +};
++
 +EventEmitter.prototype.listenerCount=functionlistenerCount(type){
 +constevents=this._events;
 if(events){
 -evlistener=events[type];
 -if(typeofevlistener==='function')
 -ret=1;
 -elseif(evlistener)
 -ret=evlistener.length;
 +constevlistener=events[type];
++
 +if(typeofevlistener==='function'){
 +return1;
 +}elseif(evlistener){
 +returnevlistener.length;
 +}
+}
 -returnret;
 +return0;
 };
 // About 1.5x faster than the two-arg version of Array#splice().
Original file line number	Diff line number	Diff line change
`@@ -1354,7 +1354,7 @@ fs.unwatchFile = function(filename, listener) {`
`1354`	`1354`	`stat.removeAllListeners('change');`
`1355`	`1355`	`}`
`1356`	`1356`
`1357`		`-if(EventEmitter.listenerCount(stat,'change')===0){`
	`1357`	`+if(stat.listenerCount('change')===0){`
`1358`	`1358`	`stat.stop();`
`1359`	`1359`	`statWatchers.delete(filename);`
`1360`	`1360`	`}`
-Original file line number
+Diff line change
 switch(key.name){
 case'c':
 -if(EventEmitter.listenerCount(this,'SIGINT')>0){
 +if(this.listenerCount('SIGINT')>0){
 this.emit('SIGINT');
 }else{
 // This readline instance is finished
 case'z':
 if(process.platform=='win32')break;
 -if(EventEmitter.listenerCount(this,'SIGTSTP')>0){
 +if(this.listenerCount('SIGTSTP')>0){
 this.emit('SIGTSTP');
 }else{
 process.once('SIGCONT',(function(self){
 stream[ESCAPE_DECODER].next();
 functiononData(b){
 -if(EventEmitter.listenerCount(stream,'keypress')>0){
 +if(stream.listenerCount('keypress')>0){
 varr=stream[KEYPRESS_DECODER].write(b);
 if(r){
 for(vari=0;i<r.length;i++){
+}
+}
 -if(EventEmitter.listenerCount(stream,'keypress')>0){
 +if(stream.listenerCount('keypress')>0){
 stream.on('data',onData);
 }else{
 stream.on('newListener',onNewListener);
Original file line number	Diff line number	Diff line change
`@@ -70,7 +70,7 @@ Stream.prototype.pipe = function(dest, options) {`
`70`	`70`	`// don't leave dangling pipes when there are errors.`
`71`	`71`	`functiononerror(er){`
`72`	`72`	`cleanup();`
`73`		`-if(EE.listenerCount(this,'error')===0){`
	`73`	`+if(this.listenerCount('error')===0){`
`74`	`74`	`thrower;// Unhandled stream error in pipe.`
`75`	`75`	`}`
`76`	`76`	`}`