microsoft / microsoft/TypeScript
No error for undeclared #private property in `.js` files
Open
Nobody has claimed this yet.
Bug
Domain: JavaScript
Effort: Moderate
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Needs Human Review
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Description
class Thing {
/**
* @param prop {string}
*/
constructor(prop) {
this.#prop = prop;
}
}
This class assigns to #prop, but it's an error to use #prop without declaring it.
This is reported as a SyntaxError, so this should report an error even outside of checkJs.
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 reproducing the provided JavaScript class with the TypeScript compiler, both with and without checkJs enabled. Trace the compiler's handling of private-property assignments and add a regression test for the undeclared #prop case. Done means the diagnostic is reported in .js files even when checkJs is disabled.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- javascript, typescript
- Domain
- compilers
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Active
- Clarity
- Clearly specified
- Newbie friendliness
- 68/100