move Error.isError to stable ES

CHANGELOG.md

@@ -1,5 +1,10 @@
 ## Changelog
 ##### Unreleased
+- [`Error.isError` proposal](https://github.com/tc39/proposal-is-error):
+  - Built-ins:
+    - `Error.isError`
+  - Moved to stable ES, May 2025 TC39 meeting
+  - Added `es.` namespace module, `/es/` and `/stable/` namespaces entries
 - Always check regular expression flags by `flags` getter [PR](https://github.com/tc39/ecma262/pull/2791). Native methods are not fixed, only own implementation updated for:
   - `RegExp.prototype[@@match]`
   - `RegExp.prototype[@@replace]`

README.md

@@ -137,6 +137,7 @@ structuredClone(new Set([1, 2, 3])); // => new Set([1, 2, 3])
       - [Change `Array` by copy](#change-array-by-copy)
       - [`Array` grouping](#array-grouping)
       - [`ArrayBuffer.prototype.transfer` and friends](#arraybufferprototypetransfer-and-friends)
+      - [`Error.isError`](#erroriserror)
       - [`Float16` methods](#float16-methods)
       - [`Iterator` helpers](#iterator-helpers)
       - [`Object.values` / `Object.entries`](#objectvalues--objectentries)
@@ -167,7 +168,6 @@ structuredClone(new Set([1, 2, 3])); // => new Set([1, 2, 3])
       - [Explicit resource management](#explicit-resource-management)
       - [`Math.sumPrecise`](#mathsumprecise)
       - [`Symbol.metadata` for decorators metadata proposal](#symbolmetadata-for-decorators-metadata-proposal)
-      - [`Error.isError`](#erroriserror)
     - [Stage 2.7 proposals](#stage-27-proposals)
       - [`Iterator` sequencing](#iterator-sequencing)
       - [`Map` upsert](#map-upsert)
@@ -627,7 +627,7 @@ console.log.bind(console, 42)(43); // => 42 43
 ```
 
 #### ECMAScript: Error[⬆](#index)
-Modules [`es.aggregate-error`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.aggregate-error.js), [`es.aggregate-error.cause`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.aggregate-error.cause.js), [`es.error.cause`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.error.cause.js), [`es.error.to-string`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.error.to-string.js).
+Modules [`es.aggregate-error`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.aggregate-error.js), [`es.aggregate-error.cause`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.aggregate-error.cause.js), [`es.error.cause`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.error.cause.js), [`es.error.is-error`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.error.is-error.js), [`es.error.to-string`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.error.to-string.js).
 ```ts
 class [
   Error,
@@ -652,6 +652,7 @@ class AggregateError extends Error {
 }
 
 class Error {
+  static isError(value: any): boolean;
   toString(): string; // different fixes
 }
 ```
@@ -660,6 +661,7 @@ class Error {
 core-js(-pure)/es|stable|actual|full/aggregate-error
 core-js/es|stable|actual|full/error
 core-js/es|stable|actual|full/error/constructor
+core-js(-pure)/es|stable|actual|full/error/is-error
 core-js/es|stable|actual|full/error/to-string
 ```
 [*Example*](https://is.gd/1SufcH):
@@ -677,6 +679,20 @@ error.cause === cause; // => true
 Error.prototype.toString.call({ message: 1, name: 2 }) === '2: 1'; // => true
 ```
 
+[*Example*](https://tinyurl.com/23nauwoz):
+```js
+Error.isError(new Error('error')); // => true
+Error.isError(new TypeError('error')); // => true
+Error.isError(new DOMException('error')); // => true
+
+Error.isError(null); // => false
+Error.isError({}); // => false
+Error.isError(Object.create(Error.prototype)); // => false
+```
+
+> [!WARNING]
+> We have no bulletproof way to polyfill this `Error.isError` / check if the object is an error, so it's an enough naive implementation.
+
 #### ECMAScript: Array[⬆](#index)
 Modules [`es.array.from`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.from.js), [`es.array.is-array`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.is-array.js), [`es.array.of`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.of.js), [`es.array.copy-within`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.copy-within.js), [`es.array.fill`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.fill.js), [`es.array.find`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.find.js), [`es.array.find-index`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.find-index.js), [`es.array.find-last`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.find-last.js), [`es.array.find-last-index`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.find-last-index.js), [`es.array.iterator`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.iterator.js), [`es.array.includes`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.includes.js), [`es.array.push`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.push.js), [`es.array.slice`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.slice.js), [`es.array.join`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.join.js), [`es.array.unshift`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.unshift.js), [`es.array.index-of`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.index-of.js), [`es.array.last-index-of`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.last-index-of.js), [`es.array.every`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.every.js), [`es.array.some`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.some.js), [`es.array.for-each`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.for-each.js), [`es.array.map`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.map.js), [`es.array.filter`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.filter.js), [`es.array.reduce`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.reduce.js), [`es.array.reduce-right`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.reduce-right.js), [`es.array.reverse`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.reverse.js), [`es.array.sort`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.sort.js), [`es.array.flat`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.flat.js), [`es.array.flat-map`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.flat-map.js), [`es.array.unscopables.flat`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.unscopables.flat.js), [`es.array.unscopables.flat-map`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.unscopables.flat-map.js), [`es.array.at`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.at.js), [`es.array.to-reversed`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.to-reversed.js), [`es.array.to-sorted`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.to-sorted.js), [`es.array.to-spliced`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.to-spliced.js), [`es.array.with`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.with.js).
 ```ts
@@ -2170,6 +2186,20 @@ class ArrayBuffer {
 core-js/proposals/array-buffer-transfer
 ```
 
+##### [`Error.isError`](https://github.com/tc39/proposal-is-error)[⬆](#index)
+```ts
+class Error {
+  static isError(value: any): boolean;
+}
+```
+[*CommonJS entry points:*](#commonjs-api)
+```
+core-js/proposals/is-error
+```
+
+> [!WARNING]
+> We have no bulletproof way to polyfill this `Error.isError` / check if the object is an error, so it's an enough naive implementation.
+
 ##### [`Float16` methods](https://github.com/tc39/proposal-float16array)[⬆](#index)
 ```ts
 class DataView {
@@ -2643,32 +2673,6 @@ core-js(-pure)/actual|full/symbol/metadata
 core-js(-pure)/actual|full/function/metadata
 ```
 
-##### [`Error.isError`](https://github.com/tc39/proposal-is-error)[⬆](#index)
-Module [`esnext.error.is-error`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/esnext.error.is-error.js)
-```ts
-class Error {
-  static isError(value: any): boolean;
-}
-```
-[*CommonJS entry points:*](#commonjs-api)
-```
-core-js/proposals/is-error
-core-js(-pure)/actual|full/error/is-error
-```
-[*Example*](https://tinyurl.com/23nauwoz):
-```js
-Error.isError(new Error('error')); // => true
-Error.isError(new TypeError('error')); // => true
-Error.isError(new DOMException('error')); // => true
-
-Error.isError(null); // => false
-Error.isError({}); // => false
-Error.isError(Object.create(Error.prototype)); // => false
-```
-
-> [!WARNING]
-> We have no bulletproof way to polyfill this method / check if the object is an error, so it's an enough naive implementation.
-
 #### Stage 2.7 proposals[⬆](#index)
 [*CommonJS entry points:*](#commonjs-api)
 ```

packages/core-js-compat/src/data.mjs

@@ -139,6 +139,15 @@ export const data = {
     rhino: '1.8.0',
     safari: '15.0',
   },
+  'es.error.is-error': {
+    // early WebKit implementation bug
+    // https://github.com/oven-sh/bun/issues/15821
+    // bun: '1.1.39',
+    chrome: '134',
+    firefox: '138',
+    // https://github.com/nodejs/node/issues/58134
+    node: false,
+  },
   'es.error.to-string': {
     chrome: '33',
     firefox: '11',
@@ -2389,15 +2398,8 @@ export const data = {
     chrome: '136', // '134', // '133',
     deno: '2.2.10',
   },
-  'esnext.error.is-error': {
-    // early WebKit implementation bug
-    // https://github.com/oven-sh/bun/issues/15821
-    // bun: '1.1.39',
-    chrome: '134',
-    firefox: '138',
-    // https://github.com/nodejs/node/issues/58134
-    node: false,
-  },
+  // TODO: Remove from `core-js@4`
+  'esnext.error.is-error': null,
   'esnext.function.demethodize': {
   },
   'esnext.function.is-callable': {
@@ -3081,6 +3083,7 @@ export const renamed = new Map([
   ['esnext.aggregate-error', 'es.aggregate-error'],
   ['esnext.data-view.get-float16', 'es.data-view.get-float16'],
   ['esnext.data-view.set-float16', 'es.data-view.set-float16'],
+  ['esnext.error.is-error', 'es.error.is-error'],
   ['esnext.global-this', 'es.global-this'],
   ['esnext.iterator.constructor', 'es.iterator.constructor'],
   ['esnext.iterator.drop', 'es.iterator.drop'],

packages/core-js-compat/src/modules-by-versions.mjs

@@ -283,4 +283,7 @@ export default {
     'es.math.f16round',
     'es.regexp.escape',
   ],
+  3.43: [
+    'es.error.is-error',
+  ],
 };

packages/core-js/actual/error/is-error.js

@@ -1,6 +1,5 @@
 'use strict';
-require('../../modules/es.object.create');
+var parent = require('../../stable/error/is-error');
 require('../../modules/esnext.error.is-error');
-var path = require('../../internals/path');
 
-module.exports = path.Error.isError;
+module.exports = parent;

packages/core-js/es/error/index.js

@@ -1,5 +1,6 @@
 'use strict';
 require('../../modules/es.error.cause');
+require('../../modules/es.error.is-error');
 require('../../modules/es.error.to-string');
 var path = require('../../internals/path');
 

packages/core-js/es/error/is-error.js

@@ -0,0 +1,6 @@
+'use strict';
+require('../../modules/es.object.create');
+require('../../modules/es.error.is-error');
+var path = require('../../internals/path');
+
+module.exports = path.Error.isError;

packages/core-js/modules/es.error.is-error.js

@@ -0,0 +1,36 @@
+'use strict';
+var $ = require('../internals/export');
+var getBuiltIn = require('../internals/get-built-in');
+var isObject = require('../internals/is-object');
+var classof = require('../internals/classof');
+var fails = require('../internals/fails');
+
+var ERROR = 'Error';
+var DOM_EXCEPTION = 'DOMException';
+// eslint-disable-next-line es/no-object-setprototypeof, no-proto -- safe
+var PROTOTYPE_SETTING_AVAILABLE = Object.setPrototypeOf || ({}).__proto__;
+
+var DOMException = getBuiltIn(DOM_EXCEPTION);
+var $Error = Error;
+var $isError = $Error.isError;
+
+var FORCED = !$isError || !PROTOTYPE_SETTING_AVAILABLE || fails(function () {
+  // Bun, isNativeError-based implementations, some buggy structuredClone-based implementations, etc.
+  // https://github.com/oven-sh/bun/issues/15821
+  return (DOMException && !$isError(new DOMException(DOM_EXCEPTION))) ||
+    // structuredClone-based implementations
+    // eslint-disable-next-line es/no-error-cause -- detection
+    !$isError(new $Error(ERROR, { cause: function () { /* empty */ } })) ||
+    // instanceof-based and FF Error#stack-based implementations
+    $isError(getBuiltIn('Object', 'create')($Error.prototype));
+});
+
+// `Error.isError` method
+// https://github.com/tc39/proposal-is-error
+$({ target: 'Error', stat: true, sham: true, forced: FORCED }, {
+  isError: function isError(arg) {
+    if (!isObject(arg)) return false;
+    var tag = classof(arg);
+    return tag === ERROR || tag === DOM_EXCEPTION;
+  }
+});

packages/core-js/modules/esnext.error.is-error.js

@@ -1,36 +1,3 @@
 'use strict';
-var $ = require('../internals/export');
-var getBuiltIn = require('../internals/get-built-in');
-var isObject = require('../internals/is-object');
-var classof = require('../internals/classof');
-var fails = require('../internals/fails');
-
-var ERROR = 'Error';
-var DOM_EXCEPTION = 'DOMException';
-// eslint-disable-next-line es/no-object-setprototypeof, no-proto -- safe
-var PROTOTYPE_SETTING_AVAILABLE = Object.setPrototypeOf || ({}).__proto__;
-
-var DOMException = getBuiltIn(DOM_EXCEPTION);
-var $Error = Error;
-var $isError = $Error.isError;
-
-var FORCED = !$isError || !PROTOTYPE_SETTING_AVAILABLE || fails(function () {
-  // Bun, isNativeError-based implementations, some buggy structuredClone-based implementations, etc.
-  // https://github.com/oven-sh/bun/issues/15821
-  return (DOMException && !$isError(new DOMException(DOM_EXCEPTION))) ||
-    // structuredClone-based implementations
-    // eslint-disable-next-line es/no-error-cause -- detection
-    !$isError(new $Error(ERROR, { cause: function () { /* empty */ } })) ||
-    // instanceof-based and FF Error#stack-based implementations
-    $isError(getBuiltIn('Object', 'create')($Error.prototype));
-});
-
-// `Error.isError` method
-// https://github.com/tc39/proposal-is-error
-$({ target: 'Error', stat: true, sham: true, forced: FORCED }, {
-  isError: function isError(arg) {
-    if (!isObject(arg)) return false;
-    var tag = classof(arg);
-    return tag === ERROR || tag === DOM_EXCEPTION;
-  }
-});
+// TODO: Remove from `core-js@4`
+require('../modules/es.error.is-error');

packages/core-js/stable/error/is-error.js

@@ -0,0 +1,4 @@
+'use strict';
+var parent = require('../../es/error/is-error');
+
+module.exports = parent;

packages/core-js/stage/3.js

@@ -5,7 +5,6 @@ require('../proposals/array-buffer-base64');
 require('../proposals/array-from-async-stage-2');
 require('../proposals/decorator-metadata-v2');
 require('../proposals/explicit-resource-management');
-require('../proposals/is-error');
 require('../proposals/json-parse-with-source');
 require('../proposals/math-sum');
 // TODO: Obsolete versions, remove from `core-js@4`

packages/core-js/stage/4.js

@@ -8,6 +8,7 @@ require('../proposals/change-array-by-copy-stage-4');
 // require('../proposals/error-cause');
 require('../proposals/float16');
 require('../proposals/global-this');
+require('../proposals/is-error');
 require('../proposals/iterator-helpers-stage-3-2');
 require('../proposals/promise-all-settled');
 require('../proposals/promise-any');

tests/compat/tests.js

@@ -419,6 +419,12 @@ GLOBAL.tests = {
     return new Error('e', { cause: 7 }).cause === 7
       && !('cause' in Error.prototype);
   },
+  'es.error.is-error': function () {
+    return PROTOTYPE_SETTING_AVAILABLE &&
+      (typeof DOMException != 'function' || Error.isError(new DOMException('DOMException'))) &&
+      Error.isError(new Error('Error', { cause: function () { /* empty */ } })) &&
+      !Error.isError(Object.create(Error.prototype));
+  },
   'es.error.to-string': function () {
     if (DESCRIPTORS_SUPPORT) {
       // Chrome 32- incorrectly call accessor
@@ -1806,12 +1812,6 @@ GLOBAL.tests = {
   'esnext.disposable-stack.constructor': function () {
     return typeof DisposableStack == 'function';
   },
-  'esnext.error.is-error': function () {
-    return PROTOTYPE_SETTING_AVAILABLE &&
-      (typeof DOMException != 'function' || Error.isError(new DOMException('DOMException'))) &&
-      Error.isError(new Error('Error', { cause: function () { /* empty */ } })) &&
-      !Error.isError(Object.create(Error.prototype));
-  },
   'esnext.function.demethodize': function () {
     return Function.prototype.demethodize;
   },

tests/entries/unit.mjs

@@ -136,6 +136,7 @@ for (PATH of ['core-js-pure', 'core-js']) {
     ok('from' in load(NS, 'array'));
     ok(load(NS, 'array/splice')([1, 2, 3], 1, 2)[0] === 2);
     ok(new (load(NS, 'error/constructor').Error)(1, { cause: 7 }).cause === 7);
+    ok(load(NS, 'error/is-error')(new Error()));
     ok(typeof load(NS, 'error/to-string') == 'function');
     ok(new (load(NS, 'error').Error)(1, { cause: 7 }).cause === 7);
     ok(load(NS, 'math/acosh')(1) === 0);
@@ -697,7 +698,6 @@ for (PATH of ['core-js-pure', 'core-js']) {
     ok(typeof load(NS, 'async-iterator/some') == 'function');
     ok(typeof load(NS, 'async-iterator/take') == 'function');
     ok(typeof load(NS, 'async-iterator/to-array') == 'function');
-    ok(load(NS, 'error/is-error')(new Error()));
     ok(load(NS, 'function/metadata') === null);
     ok(typeof load(NS, 'iterator/to-async') == 'function');
     ok(load(NS, 'json/is-raw-json')({}) === false);

tests/unit-pure/es.error.is-error.js

@@ -1,4 +1,4 @@
-import isError from 'core-js-pure/actual/error/is-error';
+import isError from 'core-js-pure/es/error/is-error';
 import create from 'core-js-pure/es/object/create';
 import AggregateError from 'core-js-pure/es/aggregate-error';
 import SuppressedError from 'core-js-pure/actual/suppressed-error';