--- /dev/null
+'use strict';
+var $ = require('../internals/export');
+var IS_PURE = require('../internals/is-pure');
+var NativePromise = require('../internals/native-promise-constructor');
+var fails = require('../internals/fails');
+var getBuiltIn = require('../internals/get-built-in');
+var speciesConstructor = require('../internals/species-constructor');
+var promiseResolve = require('../internals/promise-resolve');
+var redefine = require('../internals/redefine');
+
+// Safari bug https://bugs.webkit.org/show_bug.cgi?id=200829
+var NON_GENERIC = !!NativePromise && fails(function () {
+ NativePromise.prototype['finally'].call({ then: function () { /* empty */ } }, function () { /* empty */ });
+});
+
+// `Promise.prototype.finally` method
+// https://tc39.github.io/ecma262/#sec-promise.prototype.finally
+$({ target: 'Promise', proto: true, real: true, forced: NON_GENERIC }, {
+ 'finally': function (onFinally) {
+ var C = speciesConstructor(this, getBuiltIn('Promise'));
+ var isFunction = typeof onFinally == 'function';
+ return this.then(
+ isFunction ? function (x) {
+ return promiseResolve(C, onFinally()).then(function () { return x; });
+ } : onFinally,
+ isFunction ? function (e) {
+ return promiseResolve(C, onFinally()).then(function () { throw e; });
+ } : onFinally
+ );
+ }
+});
+
+// patch native Promise.prototype for native async functions
+if (!IS_PURE && typeof NativePromise == 'function' && !NativePromise.prototype['finally']) {
+ redefine(NativePromise.prototype, 'finally', getBuiltIn('Promise').prototype['finally']);
+}