| 'use strict'; | 
| var globalThis = require('../internals/global-this'); | 
| var NativePromiseConstructor = require('../internals/promise-native-constructor'); | 
| var isCallable = require('../internals/is-callable'); | 
| var isForced = require('../internals/is-forced'); | 
| var inspectSource = require('../internals/inspect-source'); | 
| var wellKnownSymbol = require('../internals/well-known-symbol'); | 
| var ENVIRONMENT = require('../internals/environment'); | 
| var IS_PURE = require('../internals/is-pure'); | 
| var V8_VERSION = require('../internals/environment-v8-version'); | 
|   | 
| var NativePromisePrototype = NativePromiseConstructor && NativePromiseConstructor.prototype; | 
| var SPECIES = wellKnownSymbol('species'); | 
| var SUBCLASSING = false; | 
| var NATIVE_PROMISE_REJECTION_EVENT = isCallable(globalThis.PromiseRejectionEvent); | 
|   | 
| var FORCED_PROMISE_CONSTRUCTOR = isForced('Promise', function () { | 
|   var PROMISE_CONSTRUCTOR_SOURCE = inspectSource(NativePromiseConstructor); | 
|   var GLOBAL_CORE_JS_PROMISE = PROMISE_CONSTRUCTOR_SOURCE !== String(NativePromiseConstructor); | 
|   // V8 6.6 (Node 10 and Chrome 66) have a bug with resolving custom thenables | 
|   // https://bugs.chromium.org/p/chromium/issues/detail?id=830565 | 
|   // We can't detect it synchronously, so just check versions | 
|   if (!GLOBAL_CORE_JS_PROMISE && V8_VERSION === 66) return true; | 
|   // We need Promise#{ catch, finally } in the pure version for preventing prototype pollution | 
|   if (IS_PURE && !(NativePromisePrototype['catch'] && NativePromisePrototype['finally'])) return true; | 
|   // We can't use @@species feature detection in V8 since it causes | 
|   // deoptimization and performance degradation | 
|   // https://github.com/zloirock/core-js/issues/679 | 
|   if (!V8_VERSION || V8_VERSION < 51 || !/native code/.test(PROMISE_CONSTRUCTOR_SOURCE)) { | 
|     // Detect correctness of subclassing with @@species support | 
|     var promise = new NativePromiseConstructor(function (resolve) { resolve(1); }); | 
|     var FakePromise = function (exec) { | 
|       exec(function () { /* empty */ }, function () { /* empty */ }); | 
|     }; | 
|     var constructor = promise.constructor = {}; | 
|     constructor[SPECIES] = FakePromise; | 
|     SUBCLASSING = promise.then(function () { /* empty */ }) instanceof FakePromise; | 
|     if (!SUBCLASSING) return true; | 
|   // Unhandled rejections tracking support, NodeJS Promise without it fails @@species test | 
|   } return !GLOBAL_CORE_JS_PROMISE && (ENVIRONMENT === 'BROWSER' || ENVIRONMENT === 'DENO') && !NATIVE_PROMISE_REJECTION_EVENT; | 
| }); | 
|   | 
| module.exports = { | 
|   CONSTRUCTOR: FORCED_PROMISE_CONSTRUCTOR, | 
|   REJECTION_EVENT: NATIVE_PROMISE_REJECTION_EVENT, | 
|   SUBCLASSING: SUBCLASSING | 
| }; |