Type of outer variable inside functions is not affected by narrowing in outer scope

[u130b8]

🔎 Search Terms

type inside function, scope variable, type narrowing

🕗 Version & Regression Information

• This is the behavior in every version I tried, and I reviewed the FAQ for entries about this

⏯ Playground Link

https://www.typescriptlang.org/play/?target=99&ts=5.7.0-dev.20240924#code/DYUwLgBAtghgngIxAZTAJwJYDsDmAuCAZ3WxwB8sBXYYCAXgipoG4AoWRFE3eiAIgAefNu3hJUmXGwD00iAD0A-K1YBjAPZZiEAGYBGXgAoAlPQB8EAN6sIt6GK6ScbOxFkLlAXxU7KWVWAYmroATCZWNnYc4tzOkbbuSqyeQA

💻 Code

let maybeString: string | null = null;
maybeString = "x";

maybeString;
// ^? let maybeString: string

const f1 = () => {
    maybeString;
    // ^? let maybeString: string | null
}

function f2() {
    maybeString;
    // ^? let maybeString: string | null
}

🙁 Actual behavior

The type of maybeString in both functions is string | null .

🙂 Expected behavior

The type of maybeString in both functions should be string as it was narrowed before these functions were defined.

Additional information about the issue

No response

[MartinJohns]

Duplicate of #9998.

[typescript-bot]

This issue has been marked as "Duplicate" and has seen no recent activity. It has been automatically closed for house-keeping purposes.