perf: use class instead of object literals with getters

benchmarks/fetch/request-creation.mjs

@@ -0,0 +1,8 @@
+import { bench, run } from 'mitata'
+import { Request } from '../../lib/web/fetch/request.js'
+
+const input = 'https://example.com/post'
+
+bench('new Request(input)', () => new Request(input, undefined))
+
+await run()

lib/web/fetch/request.js

@@ -41,6 +41,20 @@ const requestFinalizer = new FinalizationRegistry(({ signal, abort }) => {
 
 let patchMethodWarning = false
 
+class EnvironmentSettingsObjectBase {
+  baseUrl = getGlobalOrigin()
+
+  get origin () {
+    return this.baseUrl?.origin
+  }
+
+  policyContainer = makePolicyContainer()
+}
+
+class EnvironmentSettingsObject {
+  settingsObject = new EnvironmentSettingsObjectBase()
+}
+
 // https://fetch.spec.whatwg.org/#request-class
 class Request {
   // https://fetch.spec.whatwg.org/#dom-request
@@ -55,16 +69,9 @@ class Request {
     init = webidl.converters.RequestInit(init)
 
     // https://html.spec.whatwg.org/multipage/webappapis.html#environment-settings-object
-    this[kRealm] = {
-      settingsObject: {
-        baseUrl: getGlobalOrigin(),
-        get origin () {
-          return this.baseUrl?.origin
-        },
-        policyContainer: makePolicyContainer()
-      }
-    }
-
+    // Note: Slow initialization of object literals with getters.
+    // TODO: Remove workaround.
+    this[kRealm] = new EnvironmentSettingsObject()
     // 1. Let request be null.
     let request = null
 
@@ -366,7 +373,6 @@ class Request {
     // (https://dom.spec.whatwg.org/#dom-abortsignal-any)
     const ac = new AbortController()
     this[kSignal] = ac.signal
-    this[kSignal][kRealm] = this[kRealm]
 
     // 29. If signal is not null, then make this’s signal follow signal.
     if (signal != null) {
@@ -436,7 +442,6 @@ class Request {
     this[kHeaders] = new Headers(kConstruct)
     this[kHeaders][kHeadersList] = request.headersList
     this[kHeaders][kGuard] = 'request'
-    this[kHeaders][kRealm] = this[kRealm]
 
     // 31. If this’s request’s mode is "no-cors", then:
     if (mode === 'no-cors') {
@@ -881,11 +886,9 @@ function fromInnerRequest (innerRequest, signal, guard, realm) {
   request[kState] = innerRequest
   request[kRealm] = realm
   request[kSignal] = signal
-  request[kSignal][kRealm] = realm
   request[kHeaders] = new Headers(kConstruct)
   request[kHeaders][kHeadersList] = innerRequest.headersList
   request[kHeaders][kGuard] = guard
-  request[kHeaders][kRealm] = realm
   return request
 }
 

lib/web/fetch/response.js

@@ -29,12 +29,16 @@ const { types } = require('node:util')
 
 const textEncoder = new TextEncoder('utf-8')
 
+class EnvironmentSettingsObject {
+  settingsObject = {}
+}
+
 // https://fetch.spec.whatwg.org/#response-class
 class Response {
   // Creates network error Response.
   static error () {
     // TODO
-    const relevantRealm = { settingsObject: {} }
+    const relevantRealm = new EnvironmentSettingsObject()
 
     // The static error() method steps are to return the result of creating a
     // Response object, given a new network error, "immutable", and this’s
@@ -62,7 +66,7 @@ class Response {
 
     // 3. Let responseObject be the result of creating a Response object, given a new response,
     //    "response", and this’s relevant Realm.
-    const relevantRealm = { settingsObject: {} }
+    const relevantRealm = new EnvironmentSettingsObject()
     const responseObject = fromInnerResponse(makeResponse({}), 'response', relevantRealm)
 
     // 4. Perform initialize a response given responseObject, init, and (body, "application/json").
@@ -74,7 +78,7 @@ class Response {
 
   // Creates a redirect Response that redirects to url with status status.
   static redirect (url, status = 302) {
-    const relevantRealm = { settingsObject: {} }
+    const relevantRealm = new EnvironmentSettingsObject()
 
     webidl.argumentLengthCheck(arguments, 1, { header: 'Response.redirect' })
 
@@ -127,7 +131,7 @@ class Response {
     init = webidl.converters.ResponseInit(init)
 
     // TODO
-    this[kRealm] = { settingsObject: {} }
+    this[kRealm] = new EnvironmentSettingsObject()
 
     // 1. Set this’s response to a new response.
     this[kState] = makeResponse({})
@@ -138,7 +142,6 @@ class Response {
     this[kHeaders] = new Headers(kConstruct)
     this[kHeaders][kGuard] = 'response'
     this[kHeaders][kHeadersList] = this[kState].headersList
-    this[kHeaders][kRealm] = this[kRealm]
 
     // 3. Let bodyWithType be null.
     let bodyWithType = null
@@ -522,7 +525,6 @@ function fromInnerResponse (innerResponse, guard, realm) {
   response[kHeaders] = new Headers(kConstruct)
   response[kHeaders][kHeadersList] = innerResponse.headersList
   response[kHeaders][kGuard] = guard
-  response[kHeaders][kRealm] = realm
   return response
 }
 

test/fetch/request.js

@@ -499,8 +499,6 @@ test('fromInnerRequest', () => {
   assert.strictEqual(request[kState], innerRequest)
   assert.strictEqual(request[kRealm], realm)
   assert.strictEqual(request[kSignal], signal)
-  assert.strictEqual(request[kSignal][kRealm], realm)
   assert.strictEqual(request[kHeaders][kHeadersList], innerRequest.headersList)
   assert.strictEqual(request[kHeaders][kGuard], 'immutable')
-  assert.strictEqual(request[kHeaders][kRealm], realm)
 })

test/fetch/response.js

@@ -286,5 +286,4 @@ test('fromInnerResponse', () => {
   assert.strictEqual(response[kRealm], realm)
   assert.strictEqual(response[kHeaders][kHeadersList], innerResponse.headersList)
   assert.strictEqual(response[kHeaders][kGuard], 'immutable')
-  assert.strictEqual(response[kHeaders][kRealm], realm)
 })