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Invalid type inference for optional chaining operator when nullish check is extracted to const varaiableΒ #58632
Closed as not planned
Description
π Search Terms
"optional chaining operator", null check
π Version & Regression Information
- This is the behavior in every version I tried (from 4.4.4 to 5.5.0-dev.20240523)
β― Playground Link
π» Code
interface Foo {
a: string | null;
}
function bar(foo: Foo | null) {
const isNullish = foo?.a == null;
if (isNullish) {
return;
}
// report "Object is possibly 'null'.(2531)" for "foo.a"
console.log(foo.a.toUpperCase());
}π Actual behavior
Report an error Object is possibly 'null'.(2531) for foo.a
π Expected behavior
No error is reported
Additional information about the issue
I don't know this behavior is a bug or intended, but based on PR #44730 , I chose 'bug' for this issue.
Activity
whzx5byb commentedon May 23, 2024
Per #44730:
So just mark the property
aas readonly and it works.jet2jet commentedon May 23, 2024
Thanks for the response. I missed that this is applied only for 'a readonly property'.
I'll close the issue.