A record value should be narrowed down to array when using Array.isArray

[ficristo]

Bug Report

🔎 Search Terms

🕗 Version & Regression Information

TypeScript 4.9.4

⏯ Playground Link

Playground link with relevant code

💻 Code

function foo(id: string) {
  const record: Record<string, number | Array<number>> = {};

  const arr = record[id];

  if (Array.isArray(arr)) {
    // work
    arr.push(1);
  }
  
  if (Array.isArray(record[id])) {
    // doesn't work
    record[id].push(1);
  }
}

🙁 Actual behavior

If the record value is used directly is not narrowed down to an array.

🙂 Expected behavior

The record value type should be narrowed.

[MartinJohns]

Duplicate of #10530. Type narrowing does not occur for indexed access forms e[k] where k is not a literal.

[ficristo]

In fact using record.id does work, I didn't notice it before. Closing since it is a duplicate.
Thanks.