// Copyright (C) 2025 Michael Ficarra. All rights reserved. // This code is governed by the BSD license found in the LICENSE file. /*--- esid: sec-iterator.concat description: > Iterator.concat accesses the value of a done IteratorResult, matching the behaviour of yield* info: | Iterator.concat ( ...items ) ... 3. Let closure be a new Abstract Closure with no parameters that captures iterables and performs the following steps when called: a. For each Record iterable of iterables, do ... v. Repeat, while innerAlive is true, 1. Let iteratorResult be ? IteratorNext(iteratorRecord). 2. Let done be Completion(IteratorComplete(iteratorResult)). 3. If done is a throw completion, then a. Set iteratorRecord.[[Done]] to true. b. Return ? done. 4. Set done to ! done. 5. If done is true, then a. Set iteratorRecord.[[Done]] to true. b. Perform ? IteratorValue(iteratorResult). ... features: [iterator-sequencing] ---*/ let valueAccesses = 0; let iter = { [Symbol.iterator]() { return { next() { return { get value() { ++valueAccesses; }, done: true, }; }, }; } }; Array.from(Iterator.concat(iter, iter, iter)); assert.sameValue(valueAccesses, 3, 'Iterator.concat also accesses value getter after each iterator is done');