events: optimize EventTarget.addEventListener

Author: ronag

benchmark/events/eventtarget-add-remove-abort.js

@@ -0,0 +1,25 @@
+'use strict';
+const common = require('../common.js');
+
+const bench = common.createBenchmark(main, {
+ n: [1e5],
+ nListener: [1, 5, 10],
+});
+
+function main({ n, nListener }) {
+ const target = new EventTarget();
+ const listeners = [];
+ for (let k = 0; k < nListener; k += 1)
+ listeners.push(() => {});
+
+ bench.start();
+ for (let i = 0; i < n; i += 1) {
+ for (let k = listeners.length; --k >= 0;) {
+ target.addEventListener('abort', listeners[k]);
+ }
+ for (let k = listeners.length; --k >= 0;) {
+ target.removeEventListener('abort', listeners[k]);
+ }
+ }
+ bench.end(n);
+}

benchmark/events/eventtarget-add-remove.js

@@ -2,8 +2,8 @@
 const common = require('../common.js');
 
 const bench = common.createBenchmark(main, {
- n: [1e6],
- nListener: [5, 10],
+ n: [1e5],
+ nListener: [1, 5, 10],
 });
 
 function main({ n, nListener }) {

lib/internal/event_target.js

@@ -596,21 +596,6 @@ class EventTarget {
  throw new ERR_INVALID_THIS('EventTarget');
  if (arguments.length < 2)
  throw new ERR_MISSING_ARGS('type', 'listener');
-
- // We validateOptions before the validateListener check because the spec
- // requires us to hit getters.
- const {
- once,
- capture,
- passive,
- signal,
- isNodeStyleListener,
- weak,
- resistStopPropagation,
- } = validateEventListenerOptions(options);
-
- validateAbortSignal(signal, 'options.signal');
-
  if (!validateEventListener(listener)) {
  // The DOM silently allows passing undefined as a second argument
  // No error code for this since it is a Warning
@@ -623,19 +608,44 @@ class EventTarget {
  process.emitWarning(w);
  return;
  }
- type = webidl.converters.DOMString(type);
 
- if (signal) {
- if (signal.aborted) {
- return;
+ let once = false;
+ let capture = false;
+ let passive = false;
+ let isNodeStyleListener = false;
+ let weak = false;
+ let resistStopPropagation = false;
+
+ if (options !== kEmptyObject) {
+ // We validateOptions before the validateListener check because the spec
+ // requires us to hit getters.
+ options = validateEventListenerOptions(options);
+
+ once = options.once;
+ capture = options.capture;
+ passive = options.passive;
+ isNodeStyleListener = options.isNodeStyleListener;
+ weak = options.weak;
+ resistStopPropagation = falsoptions.resistStopPropagation;
+
+ const signal = options.signal;
+
+ validateAbortSignal(signal, 'options.signal');
+
+ if (signal) {
+ if (signal.aborted) {
+ return;
+ }
+ // TODO(benjamingr) make this weak somehow? ideally the signal would
+ // not prevent the event target from GC.
+ signal.addEventListener('abort', () => {
+ this.removeEventListener(type, listener, options);
+ }, { __proto__: null, once: true, [kWeakHandler]: this, [kResistStopPropagation]: true });
  }
- // TODO(benjamingr) make this weak somehow? ideally the signal would
- // not prevent the event target from GC.
- signal.addEventListener('abort', () => {
- this.removeEventListener(type, listener, options);
- }, { __proto__: null, once: true, [kWeakHandler]: this, [kResistStopPropagation]: true });
  }
 
+ type = webidl.converters.DOMString(type);
+
  let root = this[kEvents].get(type);
 
  if (root === undefined) {