first

node_modules/core-js/internals/promise-constructor-detection.js

@@ -0,0 +1,48 @@
+'use strict';
+var global = require('../internals/global');
+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 IS_BROWSER = require('../internals/engine-is-browser');
+var IS_DENO = require('../internals/engine-is-deno');
+var IS_PURE = require('../internals/is-pure');
+var V8_VERSION = require('../internals/engine-v8-version');
+
+var NativePromisePrototype = NativePromiseConstructor && NativePromiseConstructor.prototype;
+var SPECIES = wellKnownSymbol('species');
+var SUBCLASSING = false;
+var NATIVE_PROMISE_REJECTION_EVENT = isCallable(global.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 && (IS_BROWSER || IS_DENO) && !NATIVE_PROMISE_REJECTION_EVENT;
+});
+
+module.exports = {
+  CONSTRUCTOR: FORCED_PROMISE_CONSTRUCTOR,
+  REJECTION_EVENT: NATIVE_PROMISE_REJECTION_EVENT,
+  SUBCLASSING: SUBCLASSING
+};