From c713b84c1fe5a2eeddd25a51a930f26c496c5b10 Mon Sep 17 00:00:00 2001
From: Kevin Gibbons <bakkot@gmail.com>
Date: Sun, 18 Oct 2026 13:45:08 -0700
Subject: [PATCH 1/3] benchmark: add URLSearchParams iterator consumers
 benchmark

Assisted-by: claude:opus-5.5
Signed-off-by: Kevin Gibbons <bakkot@gmail.com>
---
 .../url-searchparams-iterator-consumers.js    | 53 +++++++++++++++++++
 1 file changed, 53 insertions(+)
 create mode 100644 benchmark/url/url-searchparams-iterator-consumers.js

diff --git a/benchmark/url/url-searchparams-iterator-consumers.js b/benchmark/url/url-searchparams-iterator-consumers.js
new file mode 100644
index 00000000000..62fff749959
--- /dev/null
+++ b/benchmark/url/url-searchparams-iterator-consumers.js
@@ -0,0 +1,53 @@
+'use strict';
+const common = require('../common.js');
+const assert = require('assert');
+
+// Consumes a URLSearchParams iterator with builtins that have fast paths for
+// iterator result objects (Array.from, Map constructor, Object.fromEntries),
+// plus for-of for comparison.
+const bench = common.createBenchmark(main, {
+  method: ['Array.from', 'Map', 'Object.fromEntries', 'for-of'],
+  n: [1e6],
+});
+
+const str = 'one=single&two=first&three=first&two=2nd&three=2nd&three=3rd';
+
+function main({ method, n }) {
+  const params = new URLSearchParams(str);
+  let noDead;
+
+  switch (method) {
+    case 'Array.from':
+      bench.start();
+      for (let i = 0; i < n; i += 1)
+        noDead = Array.from(params);
+      bench.end(n);
+      assert.strictEqual(noDead.length, 6);
+      break;
+    case 'Map':
+      bench.start();
+      for (let i = 0; i < n; i += 1)
+        noDead = new Map(params);
+      bench.end(n);
+      assert.strictEqual(noDead.size, 3);
+      break;
+    case 'Object.fromEntries':
+      bench.start();
+      for (let i = 0; i < n; i += 1)
+        noDead = Object.fromEntries(params);
+      bench.end(n);
+      assert.strictEqual(noDead.three, '3rd');
+      break;
+    case 'for-of':
+      bench.start();
+      for (let i = 0; i < n; i += 1) {
+        for (const pair of params)
+          noDead = pair;
+      }
+      bench.end(n);
+      assert.strictEqual(noDead[1], '3rd');
+      break;
+    default:
+      throw new Error(`Unknown method ${method}`);
+  }
+}

From b6bd705f27a4e29b0dc8b1f240566fa700b35f66 Mon Sep 17 00:00:00 2001
From: Kevin Gibbons <bakkot@gmail.com>
Date: Sun, 18 Oct 2026 13:46:06 -0700
Subject: [PATCH 2/3] tools: require `value` before `done` in iterator results

V8 has a fast path for `{ value, done }` literals, but it must be that order.
Also, the ES spec technically requires that order.

Assisted-by: claude:opus-5.5
Signed-off-by: Kevin Gibbons <bakkot@gmail.com>
---
 lib/eslint.config_partial.mjs                 |  2 +-
 .../test-eslint-iterator-result-done-first.js | 60 -------------------
 ...test-eslint-iterator-result-value-first.js | 60 +++++++++++++++++++
 ...irst.js => iterator-result-value-first.js} | 10 +++-
 4 files changed, 68 insertions(+), 64 deletions(-)
 delete mode 100644 test/parallel/test-eslint-iterator-result-done-first.js
 create mode 100644 test/parallel/test-eslint-iterator-result-value-first.js
 rename tools/eslint-rules/{iterator-result-done-first.js => iterator-result-value-first.js} (68%)

diff --git a/lib/eslint.config_partial.mjs b/lib/eslint.config_partial.mjs
index 9240b00ac70..fcd4dd4aa78 100644
--- a/lib/eslint.config_partial.mjs
+++ b/lib/eslint.config_partial.mjs
@@ -435,7 +435,7 @@ export default [
       'node-core/alphabetize-errors': 'error',
       'node-core/alphabetize-primordials': 'error',
       'node-core/avoid-prototype-pollution': 'error',
-      'node-core/iterator-result-done-first': 'error',
+      'node-core/iterator-result-value-first': 'error',
       'node-core/lowercase-name-for-primitive': 'error',
       'node-core/non-ascii-character': 'error',
       'node-core/no-array-destructuring': 'error',
diff --git a/test/parallel/test-eslint-iterator-result-done-first.js b/test/parallel/test-eslint-iterator-result-done-first.js
deleted file mode 100644
index f65f6bd72eb..00000000000
--- a/test/parallel/test-eslint-iterator-result-done-first.js
+++ /dev/null
@@ -1,60 +0,0 @@
-'use strict';
-
-const common = require('../common');
-if ((!common.hasCrypto) || (!common.hasIntl)) {
-  common.skip('ESLint tests require crypto and Intl');
-}
-
-common.skipIfEslintMissing();
-
-const { RuleTester } = require('../../tools/eslint/node_modules/eslint');
-const rule = require('../../tools/eslint-rules/iterator-result-done-first');
-
-const message = 'Iterator result objects should place `done` before `value`.';
-
-new RuleTester().run('iterator-result-done-first', rule, {
-  valid: [
-    'function next() { return { done: true, value: undefined }; }',
-    'function next() { return { __proto__: null, done: false, value: chunk }; }',
-    'function next() { return { done, value }; }',
-    'function next() { return { value }; }',
-    'function next() { return { done }; }',
-    'function next() { return { value: 1, other: 2 }; }',
-    'function next() { return { [value]: 1, done: true }; }',
-    'function next() { return { value: 1, [done]: true }; }',
-    'function next() { return { "done": true, "value": undefined }; }',
-    'function next() { return { ["done"]: true, ["value"]: undefined }; }',
-  ],
-  invalid: [
-    {
-      code: 'function next() { return { value: undefined, done: true }; }',
-      errors: [{ message }],
-      output: 'function next() { return { done: true, value: undefined }; }',
-    },
-    {
-      code: 'function next() { return { __proto__: null, value: chunk, done: false }; }',
-      errors: [{ message }],
-      output: 'function next() { return { __proto__: null, done: false, value: chunk }; }',
-    },
-    {
-      code: 'function next() { return { value, done }; }',
-      errors: [{ message }],
-      output: 'function next() { return { done, value }; }',
-    },
-    {
-      code: 'function next() { return { "value": undefined, "done": true }; }',
-      errors: [{ message }],
-      output: 'function next() { return { "done": true, "value": undefined }; }',
-    },
-    {
-      code: 'function next() { return { ["value"]: undefined, ["done"]: true }; }',
-      errors: [{ message }],
-      output: 'function next() { return { ["done"]: true, ["value"]: undefined }; }',
-    },
-    {
-      code: 'function next() { return { value: result, extra: true, done: false }; }',
-      errors: [{ message }],
-      output: 'function next() { return { done: false, extra: true, value: result }; }',
-    },
-  ],
-});
diff --git a/test/parallel/test-eslint-iterator-result-value-first.js b/test/parallel/test-eslint-iterator-result-value-first.js
new file mode 100644
index 00000000000..24dc56be143
--- /dev/null
+++ b/test/parallel/test-eslint-iterator-result-value-first.js
@@ -0,0 +1,60 @@
+'use strict';
+
+const common = require('../common');
+if ((!common.hasCrypto) || (!common.hasIntl)) {
+  common.skip('ESLint tests require crypto and Intl');
+}
+
+common.skipIfEslintMissing();
+
+const { RuleTester } = require('../../tools/eslint/node_modules/eslint');
+const rule = require('../../tools/eslint-rules/iterator-result-value-first');
+
+const message = 'Iterator result objects should place `value` before `done`.';
+
+new RuleTester().run('iterator-result-value-first', rule, {
+  valid: [
+    'function next() { return { value: undefined, done: true }; }',
+    'function next() { return { __proto__: null, value: chunk, done: false }; }',
+    'function next() { return { value, done }; }',
+    'function next() { return { value }; }',
+    'function next() { return { done }; }',
+    'function next() { return { done: 1, other: 2 }; }',
+    'function next() { return { [done]: 1, value: true }; }',
+    'function next() { return { done: 1, [value]: true }; }',
+    'function next() { return { "value": undefined, "done": true }; }',
+    'function next() { return { ["value"]: undefined, ["done"]: true }; }',
+  ],
+  invalid: [
+    {
+      code: 'function next() { return { done: true, value: undefined }; }',
+      errors: [{ message }],
+      output: 'function next() { return { value: undefined, done: true }; }',
+    },
+    {
+      code: 'function next() { return { __proto__: null, done: false, value: chunk }; }',
+      errors: [{ message }],
+      output: 'function next() { return { __proto__: null, value: chunk, done: false }; }',
+    },
+    {
+      code: 'function next() { return { done, value }; }',
+      errors: [{ message }],
+      output: 'function next() { return { value, done }; }',
+    },
+    {
+      code: 'function next() { return { "done": true, "value": undefined }; }',
+      errors: [{ message }],
+      output: 'function next() { return { "value": undefined, "done": true }; }',
+    },
+    {
+      code: 'function next() { return { ["done"]: true, ["value"]: undefined }; }',
+      errors: [{ message }],
+      output: 'function next() { return { ["value"]: undefined, ["done"]: true }; }',
+    },
+    {
+      code: 'function next() { return { done: false, extra: true, value: result }; }',
+      errors: [{ message }],
+      output: 'function next() { return { value: result, extra: true, done: false }; }',
+    },
+  ],
+});
diff --git a/tools/eslint-rules/iterator-result-done-first.js b/tools/eslint-rules/iterator-result-value-first.js
similarity index 68%
rename from tools/eslint-rules/iterator-result-done-first.js
rename to tools/eslint-rules/iterator-result-value-first.js
index 1c3ee9035e9..09d6fbe3027 100644
--- a/tools/eslint-rules/iterator-result-done-first.js
+++ b/tools/eslint-rules/iterator-result-value-first.js
@@ -1,6 +1,10 @@
 'use strict';
 
-const MESSAGE = 'Iterator result objects should place `done` before `value`.';
+// V8 has a fast path for `{ value, done }` literals, but it must be that order.
+// https://source.chromium.org/chromium/chromium/src/+/main:v8/src/init/bootstrapper.cc;l=746-754;drc=e8ac4914ee6b24442aed773d3a041451692b6a9c
+// Also, the ES spec technically requires that order.
+// https://tc39.es/ecma262/multipage/abstract-operations.html#sec-createiterresultobject
+const MESSAGE = 'Iterator result objects should place `value` before `done`.';
 
 function getStaticPropertyName(property) {
   const { key } = property;
@@ -48,9 +52,9 @@ module.exports = {
           }
         }
 
-        if (doneProperty && valueProperty && valueProperty.range[0] < doneProperty.range[0]) {
+        if (doneProperty && valueProperty && doneProperty.range[0] < valueProperty.range[0]) {
           context.report({
-            node: valueProperty,
+            node: doneProperty,
             message: MESSAGE,
             fix(fixer) {
               return [

From 71922e3672ffcfdefb6ca6766a9eb1473e37c2d0 Mon Sep 17 00:00:00 2001
From: Kevin Gibbons <bakkot@gmail.com>
Date: Sun, 18 Oct 2026 13:49:14 -0700
Subject: [PATCH 3/3] lib: place `value` before `done` in iterator results

Apply the iterator-result-value-first lint fixer.

Assisted-by: claude:opus-5.5
Signed-off-by: Kevin Gibbons <bakkot@gmail.com>
---
 lib/events.js                                 |  2 +-
 lib/internal/fs/promises.js                   | 10 +++----
 .../source_map/source_map_cache_map.js        |  2 +-
 lib/internal/streams/readable.js              | 18 ++++++------
 lib/internal/url.js                           |  4 +--
 lib/internal/vfs/watcher.js                   | 12 ++++----
 lib/internal/webstreams/readablestream.js     | 28 +++++++++----------
 7 files changed, 38 insertions(+), 38 deletions(-)

diff --git a/lib/events.js b/lib/events.js
index 8b20ea994d6..a2395e6dfa0 100644
--- a/lib/events.js
+++ b/lib/events.js
@@ -1043,7 +1043,7 @@ async function once(emitter, name, options = kEmptyObject) {
 }
 
 function createIterResult(value, done) {
-  return { done, value };
+  return { value, done };
 }
 
 function eventTargetAgnosticRemoveListener(emitter, name, listener, flags) {
diff --git a/lib/internal/fs/promises.js b/lib/internal/fs/promises.js
index c21b1e5740f..bc9206dd993 100644
--- a/lib/internal/fs/promises.js
+++ b/lib/internal/fs/promises.js
@@ -672,7 +672,7 @@ if (getOptionValue('--experimental-stream-iter')) {
           __proto__: null,
           next() {
             if (done) {
-              return { done: true, value: undefined };
+              return { value: undefined, done: true };
             }
             if (!started) {
               // Lock lazily, on the first read, so that an iterable that is
@@ -684,7 +684,7 @@ if (getOptionValue('--experimental-stream-iter')) {
             if (remaining === 0) {
               done = true;
               cleanup();
-              return { done: true, value: undefined };
+              return { value: undefined, done: true };
             }
             const toRead = remaining > 0 ?
               MathMin(readSize, remaining) : readSize;
@@ -700,20 +700,20 @@ if (getOptionValue('--experimental-stream-iter')) {
             if (bytesRead === 0) {
               done = true;
               cleanup();
-              return { done: true, value: undefined };
+              return { value: undefined, done: true };
             }
             if (pos >= 0) pos += bytesRead;
             if (remaining > 0) remaining -= bytesRead;
             const chunk = bytesRead < toRead ?
               buf.subarray(0, bytesRead) : buf;
-            return { done: false, value: [chunk] };
+            return { value: [chunk], done: false };
           },
           return() {
             if (!done) {
               done = true;
               if (started) cleanup();
             }
-            return { done: true, value: undefined };
+            return { value: undefined, done: true };
           },
         };
       },
diff --git a/lib/internal/source_map/source_map_cache_map.js b/lib/internal/source_map/source_map_cache_map.js
index 10561acffc4..5c144818ca7 100644
--- a/lib/internal/source_map/source_map_cache_map.js
+++ b/lib/internal/source_map/source_map_cache_map.js
@@ -104,7 +104,7 @@ class SourceMapCacheMap {
       const moduleInstance = weakRef.deref();
       if (moduleInstance == null) return next();
       const value = moduleInstance[source_map_data_private_symbol];
-      return { done: false, value: [key, value] };
+      return { value: [key, value], done: false };
     };
 
     return {
diff --git a/lib/internal/streams/readable.js b/lib/internal/streams/readable.js
index e584757dd9a..9bd7ea63691 100644
--- a/lib/internal/streams/readable.js
+++ b/lib/internal/streams/readable.js
@@ -1656,7 +1656,7 @@ function createAsyncIterator(stream, options) {
   function onChunkFulfilled(value) {
     inFlight = false;
     if (queue !== null) drain();
-    return { done: false, value };
+    return { value, done: false };
   }
 
   function onChunkRejected(err) {
@@ -1679,7 +1679,7 @@ function createAsyncIterator(stream, options) {
       if (typeof then === 'function') {
         FunctionPrototypeCall(then, chunk, (value) => {
           inFlight = false;
-          resolve({ done: false, value });
+          resolve({ value, done: false });
           if (queue !== null) drain();
         }, (err) => {
           inFlight = false;
@@ -1689,7 +1689,7 @@ function createAsyncIterator(stream, options) {
         return;
       }
       inFlight = false;
-      resolve({ done: false, value: chunk });
+      resolve({ value: chunk, done: false });
       if (queue !== null) drain();
     } else if (error) {
       inFlight = false;
@@ -1698,7 +1698,7 @@ function createAsyncIterator(stream, options) {
     } else if (error === null) {
       inFlight = false;
       finalize();
-      resolve({ done: true, value: undefined });
+      resolve({ value: undefined, done: true });
       if (queue !== null) drain();
     } else {
       // No data buffered yet; wait for 'readable' or end-of-stream and
@@ -1709,7 +1709,7 @@ function createAsyncIterator(stream, options) {
 
   function processNext(resolve, reject) {
     if (completed) {
-      resolve({ done: true, value: undefined });
+      resolve({ value: undefined, done: true });
       return;
     }
     if (!started) start();
@@ -1726,7 +1726,7 @@ function createAsyncIterator(stream, options) {
         completed = true;
       }
     }
-    resolve({ done: true, value });
+    resolve({ value, done: true });
   }
 
   function processThrow(err, reject) {
@@ -1755,7 +1755,7 @@ function createAsyncIterator(stream, options) {
             return FunctionPrototypeCall(
               then, chunk, onChunkFulfilled, onChunkRejected);
           }
-          return PromiseResolve({ done: false, value: chunk });
+          return PromiseResolve({ value: chunk, done: false });
         }
         if (error) {
           finalize();
@@ -1763,7 +1763,7 @@ function createAsyncIterator(stream, options) {
         }
         if (error === null) {
           finalize();
-          return PromiseResolve({ done: true, value: undefined });
+          return PromiseResolve({ value: undefined, done: true });
         }
         // No data buffered yet; wait for 'readable' or end-of-stream.
         inFlight = true;
@@ -1776,7 +1776,7 @@ function createAsyncIterator(stream, options) {
           queue ??= new FixedQueue();
           queue.push({ __proto__: null, type: 'next', value: undefined, resolve, reject });
         } else {
-          resolve({ done: true, value: undefined });
+          resolve({ value: undefined, done: true });
         }
       });
     },
diff --git a/lib/internal/url.js b/lib/internal/url.js
index 8c04ac70c07..456afd2242d 100644
--- a/lib/internal/url.js
+++ b/lib/internal/url.js
@@ -278,8 +278,8 @@ class URLSearchParamsIterator {
     const len = values.length;
     if (index >= len) {
       return {
-        done: true,
         value: undefined,
+        done: true,
       };
     }
 
@@ -297,8 +297,8 @@ class URLSearchParamsIterator {
     }
 
     return {
-      done: false,
       value: result,
+      done: false,
     };
   }
 
diff --git a/lib/internal/vfs/watcher.js b/lib/internal/vfs/watcher.js
index 0f23c1588b1..e48533493ef 100644
--- a/lib/internal/vfs/watcher.js
+++ b/lib/internal/vfs/watcher.js
@@ -600,7 +600,7 @@ class VFSWatchAsyncIterable {
       const event = { eventType, filename };
       if (this.#pendingResolvers.length > 0) {
         const { resolve } = this.#pendingResolvers.shift();
-        resolve({ done: false, value: event });
+        resolve({ value: event, done: false });
       } else if (this.#pendingEvents.length < kMaxPendingEvents) {
         ArrayPrototypePush(this.#pendingEvents, event);
       }
@@ -612,7 +612,7 @@ class VFSWatchAsyncIterable {
       // Resolve any pending iterators
       while (this.#pendingResolvers.length > 0) {
         const { resolve } = this.#pendingResolvers.shift();
-        resolve({ done: true, value: undefined });
+        resolve({ value: undefined, done: true });
       }
     });
 
@@ -649,12 +649,12 @@ class VFSWatchAsyncIterable {
    */
   next() {
     if (this.#closed) {
-      return PromiseResolve({ done: true, value: undefined });
+      return PromiseResolve({ value: undefined, done: true });
     }
 
     if (this.#pendingEvents.length > 0) {
       const event = this.#pendingEvents.shift();
-      return PromiseResolve({ done: false, value: event });
+      return PromiseResolve({ value: event, done: false });
     }
 
     return new Promise((resolve, reject) => {
@@ -668,7 +668,7 @@ class VFSWatchAsyncIterable {
    */
   return() {
     this.#watcher.close();
-    return PromiseResolve({ done: true, value: undefined });
+    return PromiseResolve({ value: undefined, done: true });
   }
 
   /**
@@ -678,7 +678,7 @@ class VFSWatchAsyncIterable {
    */
   throw(error) {
     this.#watcher.close();
-    return PromiseResolve({ done: true, value: undefined });
+    return PromiseResolve({ value: undefined, done: true });
   }
 }
 
diff --git a/lib/internal/webstreams/readablestream.js b/lib/internal/webstreams/readablestream.js
index f19337f5b6b..a5c4415785d 100644
--- a/lib/internal/webstreams/readablestream.js
+++ b/lib/internal/webstreams/readablestream.js
@@ -710,14 +710,14 @@ class ReadableStreamAsyncIteratorReadRequest {
 
   [kChunk](chunk) {
     this.current = undefined;
-    this.promise.resolve({ done: false, value: chunk });
+    this.promise.resolve({ value: chunk, done: false });
   }
 
   [kClose]() {
     this.current = undefined;
     this.done = true;
     readableStreamReaderGenericRelease(this.reader);
-    this.promise.resolve({ done: true, value: undefined });
+    this.promise.resolve({ value: undefined, done: true });
   }
 
   [kError](error) {
@@ -733,7 +733,7 @@ class ReadableStreamAsyncIteratorReadRequest {
 // promise allocations.
 function readableStreamAsyncIteratorNextSteps(state) {
   if (state.done)
-    return PromiseResolve({ done: true, value: undefined });
+    return PromiseResolve({ value: undefined, done: true });
 
   const reader = state.reader;
   if (reader[kState].stream === undefined) {
@@ -751,7 +751,7 @@ function readableStreamAsyncIteratorNextSteps(state) {
 // Not an async function either: the cancel path settles one microtask
 // after the cancel promise, exactly as `await` would.
 function readableStreamAsyncIteratorReturnSteps(state, value) {
-  const iterResult = { done: true, value };
+  const iterResult = { value, done: true };
   if (state.done)
     return PromiseResolve(iterResult);
   state.done = true;
@@ -839,16 +839,16 @@ class ReadableStreamAsyncIterator {
             readableStreamDefaultControllerPull(controller);
           }
 
-          return PromiseResolve({ done: false, value: chunk });
+          return PromiseResolve({ value: chunk, done: false });
         }
       } else if (controller[kState].queueTotalSize > 0) {
         // Byte controller with buffered data: same shape as above via
         // the queue-filled arm of the byte controller's pull steps.
         stream[kState].disturbed = true;
         return PromiseResolve({
-          done: false,
-
           value: readableByteStreamControllerDequeueChunk(controller),
+
+          done: false,
         });
       }
     }
@@ -889,11 +889,11 @@ class DefaultReadRequest {
   }
 
   [kChunk](value) {
-    this[kState].resolve({ done: false, value });
+    this[kState].resolve({ value, done: false });
   }
 
   [kClose]() {
-    this[kState].resolve({ done: true, value: undefined });
+    this[kState].resolve({ value: undefined, done: true });
   }
 
   [kError](error) {
@@ -934,11 +934,11 @@ class ReadIntoRequest {
   }
 
   [kChunk](value) {
-    this[kState].resolve({ done: false, value });
+    this[kState].resolve({ value, done: false });
   }
 
   [kClose](value) {
-    this[kState].resolve({ done: true, value });
+    this[kState].resolve({ value, done: true });
   }
 
   [kError](error) {
@@ -1007,7 +1007,7 @@ class ReadableStreamDefaultReader {
             readableStreamDefaultControllerPull(controller);
           }
 
-          return PromiseResolve({ done: false, value: chunk });
+          return PromiseResolve({ value: chunk, done: false });
         }
       } else if (controller[kState].queueTotalSize > 0) {
         // Byte controller with buffered data: mirror the queue-filled arm
@@ -1015,9 +1015,9 @@ class ReadableStreamDefaultReader {
         // the read request.
         stream[kState].disturbed = true;
         return PromiseResolve({
-          done: false,
-
           value: readableByteStreamControllerDequeueChunk(controller),
+
+          done: false,
         });
       }
     }