From 06c316bb664310ea3a39e3dd78b82e9b5b2efcb0 Mon Sep 17 00:00:00 2001
From: Denis Pushkarev <zloirock@zloirock.ru>
Date: Wed, 14 Dec 2022 08:59:10 +0700
Subject: [PATCH] fix handling of sparse arrays in `structuredClone`, close
 #1156

---
 CHANGELOG.md                                     | 1 +
 packages/core-js/modules/web.structured-clone.js | 3 ++-
 tests/unit-global/web.structured-clone.js        | 1 +
 tests/unit-pure/web.structured-clone.js          | 1 +
 4 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9ff966ba589a..3d0ef4e63899 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -74,6 +74,7 @@
   - Added Samsung Internet 19.0 compat data mapping
   - Added Quest Browser 24.0 compat data mapping
   - Fixed the first version in the Chromium-based Edge compat data mapping
+- Fixed handling of sparse arrays in `structuredClone`, [#1156](https://github.com/zloirock/core-js/issues/1156)
 - `{ Map, WeakMap }.prototype.emplace` became stricter [by the spec draft](https://tc39.es/proposal-upsert/)
 - Fixed a theoretically possible future conflict of polyfills definitions in the pure version
 - Added pure version of the `Number` constructor, [#1154](https://github.com/zloirock/core-js/issues/1154), [#1155](https://github.com/zloirock/core-js/issues/1155), thanks [@trosos](https://github.com/trosos)
diff --git a/packages/core-js/modules/web.structured-clone.js b/packages/core-js/modules/web.structured-clone.js
index acd2b3f36eab..75c598089049 100644
--- a/packages/core-js/modules/web.structured-clone.js
+++ b/packages/core-js/modules/web.structured-clone.js
@@ -28,6 +28,7 @@ var IS_DENO = require('../internals/engine-is-deno');
 var IS_NODE = require('../internals/engine-is-node');
 
 var Object = global.Object;
+var Array = global.Array;
 var Date = global.Date;
 var Error = global.Error;
 var EvalError = global.EvalError;
@@ -153,7 +154,7 @@ var structuredCloneInternal = function (value, map) {
 
   switch (type) {
     case 'Array':
-      cloned = [];
+      cloned = Array(lengthOfArrayLike(value));
       deep = true;
       break;
     case 'Object':
diff --git a/tests/unit-global/web.structured-clone.js b/tests/unit-global/web.structured-clone.js
index b4c91156d22d..576e061f5e36 100644
--- a/tests/unit-global/web.structured-clone.js
+++ b/tests/unit-global/web.structured-clone.js
@@ -239,6 +239,7 @@ QUnit.module('structuredClone', () => {
     const arrays = [
       [],
       [1, 2, 3],
+      Array(1),
       assign(
         ['foo', 'bar'],
         { 10: true, 11: false, 20: 123, 21: 456, 30: null }),
diff --git a/tests/unit-pure/web.structured-clone.js b/tests/unit-pure/web.structured-clone.js
index cf6cd451ed03..b577d1af27c6 100644
--- a/tests/unit-pure/web.structured-clone.js
+++ b/tests/unit-pure/web.structured-clone.js
@@ -247,6 +247,7 @@ QUnit.module('structuredClone', () => {
     const arrays = [
       [],
       [1, 2, 3],
+      Array(1),
       assign(
         ['foo', 'bar'],
         { 10: true, 11: false, 20: 123, 21: 456, 30: null }),