microsoft / microsoft/TypeScript

Async generator typing

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#42,055 0 comments 1 reaction 0 assignees View on GitHub

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Needs Investigation Rescheduled
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Description

v4.1.2

Code:

async function* foo() {}
foo().next(); // error

Result:

Return type of foo is {}

Expected:

Should be AsyncGenerator


Edit: apparently this isn't a bug with TS per se, however it still affects intellisense in vscode for vanilla JS.

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the async generator reproduction in the issue and compare the reported return type with the expected AsyncGenerator type. Trace how TypeScript analyzes vanilla JavaScript for VS Code IntelliSense, then verify that foo().next() receives the expected type and that the original example no longer reports an error.

Written by the indexing model from the issue text.

Assessment

Tech stack
javascript, typescript, vscode
Domain
developer-experience, devtools
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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