add Object.prototype.__proto__ polyfill

Author: zloirock

CHANGELOG.md

@@ -1,5 +1,9 @@
 ## Changelog
 ##### Unreleased
+- Added `Object.prototype.__proto__` polyfill
+  - Only for modern engines where this feature is missed (like Deno), it's not installed in IE10- since here we have no proper way setting of the prototype
+  - Without fixes of early implementations where it's not an accessor since those fixes are impossible
+  - Only for the global version
 - Considering `document.all` as an object in some missed cases, see [ECMAScript Annex B 3.6](https://tc39.es/ecma262/#sec-IsHTMLDDA-internal-slot)
 - Avoiding unnecessary promise creation and validation result in `%WrapForValid(Async)IteratorPrototype%.return`, [proposal-iterator-helpers/215](https://github.com/tc39/proposal-iterator-helpers/pull/215)
 - Fixed omitting the result of proxing `.return` in `%IteratorHelperPrototype%.return`, [#1116](https://github.com/zloirock/core-js/issues/1116)

README.md

@@ -438,18 +438,16 @@ core-js(-pure)
 core-js(-pure)/es
 ```
 #### ECMAScript: Object[⬆](#index)
-Modules [`es.object.assign`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.assign.js), [`es.object.is`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.is.js), [`es.object.set-prototype-of`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.set-prototype-of.js), [`es.object.to-string`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.to-string.js), [`es.object.freeze`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.freeze.js), [`es.object.seal`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.seal.js), [`es.object.prevent-extensions`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.prevent-extensions.js), [`es.object.is-frozen`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.is-frozen.js), [`es.object.is-sealed`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.is-sealed.js), [`es.object.is-extensible`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.is-extensible.js), [`es.object.get-own-property-descriptor`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.get-own-property-descriptor.js), [`es.object.get-own-property-descriptors`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.get-own-property-descriptors.js), [`es.object.get-prototype-of`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.get-prototype-of.js), [`es.object.keys`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.keys.js), [`es.object.values`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.values.js), [`es.object.entries`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.entries.js), [`es.object.get-own-property-names`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.get-own-property-names.js), [`es.object.from-entries`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.from-entries.js), [`es.object.has-own`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.has-own.js).
+Modules [`es.object.assign`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.assign.js), [`es.object.create`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.create.js), [`es.object.define-getter`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.define-getter.js), [`es.object.define-property`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.define-property.js), [`es.object.define-properties`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.es.object.define-properties.js), [`es.object.define-setter`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.define-setter.js), [`es.object.entries`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.entries.js), [`es.object.freeze`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.freeze.js), [`es.object.from-entries`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.from-entries.js), [`es.object.get-own-property-descriptor`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.get-own-property-descriptor.js), [`es.object.get-own-property-descriptors`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.get-own-property-descriptors.js), [`es.object.get-own-property-names`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.get-own-property-names.js), [`es.object.get-prototype-of`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.get-prototype-of.js), [`es.object.has-own`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.has-own.js), [`es.object.is`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.is.js), [`es.object.is-extensible`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.is-extensible.js), [`es.object.is-frozen`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.is-frozen.js), [`es.object.is-sealed`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.is-sealed.js), [`es.object.keys`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.keys.js), [`es.object.lookup-setter`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.lookup-setter.js), [`es.object.lookup-getter`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.lookup-getter.js), [`es.object.prevent-extensions`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.prevent-extensions.js), [`es.object.proto`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.proto.js), [`es.object.to-string`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.to-string.js), [`es.object.seal`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.seal.js), [`es.object.set-prototype-of`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.set-prototype-of.js), [`es.object.values`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.values.js).
 
-Just ES5 features: [`es.object.create`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.create.js), [`es.object.define-property`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.define-property.js) and [`es.object.define-properties`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.es.object.define-properties.js).
-
-[ES2017 Annex B](https://tc39.es/ecma262/#sec-object.prototype.__defineGetter__) - modules [`es.object.define-setter`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.define-setter.js), [`es.object.define-getter`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.define-getter.js), [`es.object.lookup-setter`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.lookup-setter.js) and [`es.object.lookup-getter`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.lookup-getter.js)
 ```js
 class Object {
   toString(): string; // ES2015+ fix: @@toStringTag support
   __defineGetter__(property: PropertyKey, getter: Function): void;
   __defineSetter__(property: PropertyKey, setter: Function): void;
   __lookupGetter__(property: PropertyKey): Function | void;
   __lookupSetter__(property: PropertyKey): Function | void;
+  __proto__: Object | null; // required a way setting of prototype - will not in IE10-, it's for modern engines like Deno
   static assign(target: Object, ...sources: Array<Object>): Object;
   static create(prototype: Object | null, properties?: { [property: PropertyKey]: PropertyDescriptor }): Object;
   static defineProperties(object: Object, properties: { [property: PropertyKey]: PropertyDescriptor })): Object;
@@ -494,6 +492,7 @@ core-js(-pure)/es|stable|actual|full/object/freeze
 core-js(-pure)/es|stable|actual|full/object/from-entries
 core-js(-pure)/es|stable|actual|full/object/seal
 core-js(-pure)/es|stable|actual|full/object/prevent-extensions
+core-js/es|stable|actual|full/object/proto
 core-js(-pure)/es|stable|actual|full/object/is-frozen
 core-js(-pure)/es|stable|actual|full/object/is-sealed
 core-js(-pure)/es|stable|actual|full/object/is-extensible

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

@@ -1115,6 +1115,16 @@ export const data = {
     safari: '9.0',
     rhino: '1.7.13',
   },
+  'es.object.proto': {
+    bun: '0.1.1',
+    chrome: '5',
+    deno: false,
+    firefox: '2',
+    hermes: '0.1',
+    ie: '11',
+    opera: '10.50',
+    safari: '3.1',
+  },
   'es.object.seal': {
     bun: '0.1.1',
     chrome: '44',

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

@@ -154,4 +154,7 @@ export default {
     'esnext.async-iterator.indexed',
     'esnext.iterator.indexed',
   ],
+  3.25: [
+    'es.object.proto',
+  ],
 };

packages/core-js-pure/override/modules/es.object.proto.js

@@ -0,0 +1 @@
+// empty

packages/core-js/actual/object/proto.js

@@ -0,0 +1,3 @@
+var parent = require('../../stable/object/proto');
+
+module.exports = parent;

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

@@ -17,6 +17,7 @@ require('../../modules/es.object.is-frozen');
 require('../../modules/es.object.is-sealed');
 require('../../modules/es.object.keys');
 require('../../modules/es.object.prevent-extensions');
+require('../../modules/es.object.proto');
 require('../../modules/es.object.seal');
 require('../../modules/es.object.set-prototype-of');
 require('../../modules/es.object.values');

packages/core-js/es/object/proto.js

@@ -0,0 +1 @@
+require('../../modules/es.object.proto');

packages/core-js/full/object/proto.js

@@ -0,0 +1,3 @@
+var parent = require('../../actual/object/proto');
+
+module.exports = parent;

packages/core-js/modules/es.object.proto.js

@@ -0,0 +1,29 @@
+'use strict';
+var DESCRIPTORS = require('../internals/descriptors');
+var defineBuiltInAccessor = require('../internals/define-built-in-accessor');
+var isObject = require('../internals/is-object');
+var toObject = require('../internals/to-object');
+var requireObjectCoercible = require('../internals/require-object-coercible');
+
+// eslint-disable-next-line es-x/no-object-getprototypeof -- safe
+var getPrototypeOf = Object.getPrototypeOf;
+// eslint-disable-next-line es-x/no-object-setprototypeof -- safe
+var setPrototypeOf = Object.setPrototypeOf;
+var ObjectPrototype = Object.prototype;
+var PROTO = '__proto__';
+
+// `Object.prototype.__proto__` accessor
+// https://tc39.es/ecma262/#sec-object.prototype.__proto__
+if (DESCRIPTORS && getPrototypeOf && setPrototypeOf && !(PROTO in ObjectPrototype)) try {
+  defineBuiltInAccessor(ObjectPrototype, PROTO, {
+    configurable: true,
+    get: function __proto__() {
+      return getPrototypeOf(toObject(this));
+    },
+    set: function __proto__(proto) {
+      var O = requireObjectCoercible(this);
+      if (!isObject(proto) && proto !== null || !isObject(O)) return;
+      setPrototypeOf(O, proto);
+    }
+  });
+} catch (error) { /* empty */ }

packages/core-js/stable/object/proto.js

@@ -0,0 +1,3 @@
+var parent = require('../../es/object/proto');
+
+module.exports = parent;

scripts/build-compat-data.mjs

@@ -4,6 +4,8 @@ import external from 'core-js-compat/src/external.mjs';
 import mappings from 'core-js-compat/src/mapping.mjs';
 import helpers from 'core-js-compat/helpers.js';
 
+const { compare, has, semver, sortObjectByKey } = helpers;
+
 for (const scope of [data, external]) {
   for (const [key, module] of Object.entries(scope)) {
     const { chrome, ie } = module;
@@ -12,21 +14,21 @@ for (const scope of [data, external]) {
       const [engine, targetKey] = mappingKey.split('To')
         .map(it => it.replace(/([a-z])([A-Z])/, (_, a, b) => `${ a }_${ b }`).toLowerCase());
       const version = module[engine];
-      if (!version || module[targetKey]) return;
+      if (!version || has(module, targetKey)) return;
       const mapping = mappings[mappingKey];
       if (typeof mapping == 'function') {
         return module[targetKey] = String(mapping(version));
       }
-      const source = helpers.semver(version);
+      const source = semver(version);
       for (const [from, to] of mapping) {
-        if (helpers.compare(source, '<=', from)) {
+        if (compare(source, '<=', from)) {
           return module[targetKey] = String(to);
         }
       }
     }
 
     map('ChromeToAndroid');
-    if (!module.android && chrome) {
+    if (!has(module, 'android') && chrome) {
       module.android = String(Math.max(chrome, 37));
     }
     if (key.startsWith('es')) {
@@ -35,7 +37,7 @@ for (const scope of [data, external]) {
     if (/^(?:es|esnext|web)\./.test(key)) {
       map('ChromeToElectron');
     }
-    if (!module.edge) {
+    if (!has(module, 'edge')) {
       if (ie && !key.includes('immediate')) {
         module.edge = '12';
       } else if (chrome) {
@@ -46,7 +48,7 @@ for (const scope of [data, external]) {
       map('ChromeToNode');
     }
     map('ChromeToOpera');
-    if (!module.opera_mobile && module.opera <= 42) {
+    if (!has(module, 'opera_mobile') && module.opera <= 42) {
       module.opera_mobile = module.opera;
     } else {
       map('ChromeToOperaMobile');
@@ -56,7 +58,11 @@ for (const scope of [data, external]) {
     map('SafariToIOS');
     map('SafariToPhantom');
 
-    scope[key] = helpers.sortObjectByKey(module);
+    for (const [engine, version] of Object.entries(module)) {
+      if (!version) delete module[engine];
+    }
+
+    scope[key] = sortObjectByKey(module);
   }
 }
 

tests/commonjs.mjs

@@ -34,6 +34,7 @@ for (PATH of ['core-js-pure', 'core-js']) {
     ok(!load(NS, 'object/is-sealed')({}));
     ok(load(NS, 'object/keys')({ q: 0 })[0] === 'q');
     ok(load(NS, 'object/prevent-extensions')({}));
+    load(NS, 'object/proto');
     ok(load(NS, 'object/seal')({}));
     ok(load(NS, 'object/set-prototype-of')({}, []) instanceof Array);
     ok(load(NS, 'object/to-string')([]) === '[object Array]');

tests/compat/tests.js

@@ -838,6 +838,9 @@ GLOBAL.tests = {
   'es.object.prevent-extensions': function () {
     return Object.preventExtensions(true);
   },
+  'es.object.proto': function () {
+    return '__proto__' in Object.prototype;
+  },
   'es.object.seal': function () {
     return Object.seal(true);
   },

tests/tests/es.object.proto.js

@@ -0,0 +1,14 @@
+/* eslint-disable no-proto -- required for testing */
+import { DESCRIPTORS, PROTO } from '../helpers/constants';
+
+if (PROTO && DESCRIPTORS) QUnit.test('Object.prototype.__proto__', assert => {
+  assert.true('__proto__' in Object.prototype, 'in Object.prototype');
+  const O = {};
+  assert.same(O.__proto__, Object.prototype);
+  O.__proto__ = Array.prototype;
+  assert.same(O.__proto__, Array.prototype);
+  assert.same(Object.getPrototypeOf(O), Array.prototype);
+  assert.true(O instanceof Array);
+  O.__proto__ = null;
+  assert.same(Object.getPrototypeOf(O), null);
+});