create fast MessageEvent

benchmarks/websocket/messageevent.mjs

@@ -0,0 +1,20 @@
+import { bench, group, run } from 'mitata'
+import { createFastMessageEvent, MessageEvent as UndiciMessageEvent } from '../../lib/web/websocket/events.js'
+
+const { port1, port2 } = new MessageChannel()
+
+group('MessageEvent instantiation', () => {
+  bench('undici - fast MessageEvent init', () => {
+    return createFastMessageEvent('event', { data: null, ports: [port1, port2] })
+  })
+
+  bench('undici - MessageEvent init', () => {
+    return new UndiciMessageEvent('event', { data: null, ports: [port1, port2] })
+  })
+
+  bench('global - MessageEvent init', () => {
+    return new MessageEvent('event', { data: null, ports: [port1, port2] })
+  })
+})
+
+await run()

index-fetch.js

@@ -17,11 +17,12 @@ module.exports.Headers = require('./lib/web/fetch/headers').Headers
 module.exports.Response = require('./lib/web/fetch/response').Response
 module.exports.Request = require('./lib/web/fetch/request').Request
 
-const { CloseEvent, ErrorEvent, MessageEvent } = require('./lib/web/websocket/events')
+const { CloseEvent, ErrorEvent, MessageEvent, createFastMessageEvent } = require('./lib/web/websocket/events')
 module.exports.WebSocket = require('./lib/web/websocket/websocket').WebSocket
 module.exports.CloseEvent = CloseEvent
 module.exports.ErrorEvent = ErrorEvent
 module.exports.MessageEvent = MessageEvent
+module.exports.createFastMessageEvent = createFastMessageEvent
 
 module.exports.EventSource = require('./lib/web/eventsource/eventsource').EventSource
 

lib/web/eventsource/eventsource.js

@@ -6,7 +6,7 @@ const { makeRequest } = require('../fetch/request')
 const { webidl } = require('../fetch/webidl')
 const { EventSourceStream } = require('./eventsource-stream')
 const { parseMIMEType } = require('../fetch/data-url')
-const { MessageEvent } = require('../websocket/events')
+const { createFastMessageEvent } = require('../websocket/events')
 const { isNetworkError } = require('../fetch/response')
 const { delay } = require('./util')
 const { kEnumerableProperty } = require('../../core/util')
@@ -290,7 +290,7 @@ class EventSource extends EventTarget {
       const eventSourceStream = new EventSourceStream({
         eventSourceSettings: this.#state,
         push: (event) => {
-          this.dispatchEvent(new MessageEvent(
+          this.dispatchEvent(createFastMessageEvent(
             event.type,
             event.options
           ))

lib/web/websocket/connection.js

@@ -267,7 +267,7 @@ function onSocketClose () {
   //    decode without BOM to the WebSocket connection close
   //    reason.
   // TODO: process.nextTick
-  fireEvent('close', ws, CloseEvent, {
+  fireEvent('close', ws, (type, init) => new CloseEvent(type, init), {
     wasClean, code, reason
   })
 

lib/web/websocket/events.js

@@ -2,6 +2,7 @@
 
 const { webidl } = require('../fetch/webidl')
 const { kEnumerableProperty } = require('../../core/util')
+const { kConstruct } = require('../../core/symbols')
 const { MessagePort } = require('node:worker_threads')
 
 /**
@@ -11,6 +12,11 @@ class MessageEvent extends Event {
   #eventInit
 
   constructor (type, eventInitDict = {}) {
+    if (type === kConstruct) {
+      super(arguments[1], arguments[2])
+      return
+    }
+
     webidl.argumentLengthCheck(arguments, 1, { header: 'MessageEvent constructor' })
 
     type = webidl.converters.DOMString(type)
@@ -73,8 +79,22 @@ class MessageEvent extends Event {
       bubbles, cancelable, data, origin, lastEventId, source, ports
     })
   }
+
+  static createFastMessageEvent (type, init) {
+    const messageEvent = new MessageEvent(kConstruct, type, init)
+    messageEvent.#eventInit = init
+    messageEvent.#eventInit.data ??= null
+    messageEvent.#eventInit.origin ??= ''
+    messageEvent.#eventInit.lastEventId ??= ''
+    messageEvent.#eventInit.source ??= null
+    messageEvent.#eventInit.ports ??= []
+    return messageEvent
+  }
 }
 
+const { createFastMessageEvent } = MessageEvent
+delete MessageEvent.createFastMessageEvent
+
 /**
  * @see https://websockets.spec.whatwg.org/#the-closeevent-interface
  */
@@ -299,5 +319,6 @@ webidl.converters.ErrorEventInit = webidl.dictionaryConverter([
 module.exports = {
   MessageEvent,
   CloseEvent,
-  ErrorEvent
+  ErrorEvent,
+  createFastMessageEvent
 }

lib/web/websocket/util.js

@@ -2,7 +2,7 @@
 
 const { kReadyState, kController, kResponse, kBinaryType, kWebSocketURL } = require('./symbols')
 const { states, opcodes } = require('./constants')
-const { MessageEvent, ErrorEvent } = require('./events')
+const { ErrorEvent, createFastMessageEvent } = require('./events')
 const { isUtf8 } = require('node:buffer')
 
 /* globals Blob */
@@ -51,15 +51,16 @@ function isClosed (ws) {
  * @see https://dom.spec.whatwg.org/#concept-event-fire
  * @param {string} e
  * @param {EventTarget} target
+ * @param {(...args: ConstructorParameters<typeof Event>) => Event} eventFactory
  * @param {EventInit | undefined} eventInitDict
  */
-function fireEvent (e, target, eventConstructor = Event, eventInitDict = {}) {
+function fireEvent (e, target, eventFactory = (type, init) => new Event(type, init), eventInitDict = {}) {
   // 1. If eventConstructor is not given, then let eventConstructor be Event.
 
   // 2. Let event be the result of creating an event given eventConstructor,
   //    in the relevant realm of target.
   // 3. Initialize event’s type attribute to e.
-  const event = new eventConstructor(e, eventInitDict) // eslint-disable-line new-cap
+  const event = eventFactory(e, eventInitDict)
 
   // 4. Initialize any other IDL attributes of event as described in the
   //    invocation of this algorithm.
@@ -110,7 +111,7 @@ function websocketMessageReceived (ws, type, data) {
   // 3. Fire an event named message at the WebSocket object, using MessageEvent,
   //    with the origin attribute initialized to the serialization of the WebSocket
   //    object’s url's origin, and the data attribute initialized to dataForEvent.
-  fireEvent('message', ws, MessageEvent, {
+  fireEvent('message', ws, createFastMessageEvent, {
     origin: ws[kWebSocketURL].origin,
     data: dataForEvent
   })
@@ -195,7 +196,7 @@ function failWebsocketConnection (ws, reason) {
 
   if (reason) {
     // TODO: process.nextTick
-    fireEvent('error', ws, ErrorEvent, {
+    fireEvent('error', ws, (type, init) => new ErrorEvent(type, init), {
       error: new Error(reason)
     })
   }