microsoft / microsoft/TypeScript
Support for `Object.hasOwn` (`lib.d.ts` and narrowing)
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Domain: lib.d.ts
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Description
Object.hasOwn(obj, key) has just moved to stage 3.
https://github.com/tc39/proposal-accessible-object-hasownproperty
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by reading the existing Object declarations in lib.d.ts and the proposal linked in the issue, then trace how narrowing is handled for built-in predicates. Done means Object.hasOwn is represented in lib.d.ts and its use provides the intended narrowing behavior, with the relevant compiler tests updated or added.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- javascript, typescript
- Domain
- compilers
- Issue type
- Feature
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Quiet
- Clarity
- Mostly clear
- Newbie friendliness
- 50/100