René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"stream/iter: fromSync() rejects dual sync/async iterables instead of using Symbol.iterator","articleBody":"### Version\n\nmain\n\n### Platform\n\n```text\nmacOS 26.5.0\n```\n\n### Subsystem\n\nstream\n\n### What steps will reproduce the bug?\n\n```js\nimport { fromSync, textSync } from 'node:stream/iter';\n\nconst input = {\n  *[Symbol.iterator]() {\n    yield new TextEncoder().encode('sync');\n  },\n  async *[Symbol.asyncIterator]() {\n    yield new TextEncoder().encode('async');\n  },\n};\n\ntry {\n  console.log(textSync(fromSync(input)));\n} catch (err) {\n  console.log(`${err.name}: ${err.message}`);\n}\n```\n\n### How often does it reproduce? Is there a required condition?\n\nAlways\n\n### What is the expected behavior? Why is that the expected behavior?\n\n```console\nsync\n```\n\n`fromSync()` currently rejects any object with `Symbol.asyncIterator` before checking for `Symbol.iterator`. Per Spec [§8.2](https://stream-iter.jasnell.me/#fromsync-method), only async-only inputs should be rejected here; a dual sync+async iterable should be accepted through its synchronous iterator.\n\n\n### What do you see instead?\n\n```console\nTypeError: The \"input\" argument must be an a synchronous input (not AsyncIterable). Received an instance of Object\n```\n\n### Additional information\n\n_No response_","author":{"url":"https://github.com/trivikr","@type":"Person","name":"trivikr"},"datePublished":"2026-07-04T22:24:59.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/64292/node/issues/64292"}