--- /dev/null
+'use strict';
+var bind = require('../internals/function-bind-context');
+var toObject = require('../internals/to-object');
+var isConstructor = require('../internals/is-constructor');
+var getAsyncIterator = require('../internals/get-async-iterator');
+var getIterator = require('../internals/get-iterator');
+var getIteratorMethod = require('../internals/get-iterator-method');
+var getMethod = require('../internals/get-method');
+var getVirtual = require('../internals/entry-virtual');
+var getBuiltIn = require('../internals/get-built-in');
+var wellKnownSymbol = require('../internals/well-known-symbol');
+var AsyncFromSyncIterator = require('../internals/async-from-sync-iterator');
+var toArray = require('../internals/async-iterator-iteration').toArray;
+
+var ASYNC_ITERATOR = wellKnownSymbol('asyncIterator');
+var arrayIterator = getVirtual('Array').values;
+
+// `Array.fromAsync` method implementation
+// https://github.com/tc39/proposal-array-from-async
+module.exports = function fromAsync(asyncItems /* , mapfn = undefined, thisArg = undefined */) {
+ var C = this;
+ var argumentsLength = arguments.length;
+ var mapfn = argumentsLength > 1 ? arguments[1] : undefined;
+ var thisArg = argumentsLength > 2 ? arguments[2] : undefined;
+ return new (getBuiltIn('Promise'))(function (resolve) {
+ var O = toObject(asyncItems);
+ if (mapfn !== undefined) mapfn = bind(mapfn, thisArg);
+ var usingAsyncIterator = getMethod(O, ASYNC_ITERATOR);
+ var usingSyncIterator = usingAsyncIterator ? undefined : getIteratorMethod(O) || arrayIterator;
+ var A = isConstructor(C) ? new C() : [];
+ var iterator = usingAsyncIterator
+ ? getAsyncIterator(O, usingAsyncIterator)
+ : new AsyncFromSyncIterator(getIterator(O, usingSyncIterator));
+ resolve(toArray(iterator, mapfn, A));
+ });
+};