array.every not working consistently

[damianobarbati]

Bug Report

array.every on union string[][] | string[][][]; throws a This expression is not callable..

🔎 Search Terms

• array.every not callable
• .every not callable
• every not callable

🕗 Version & Regression Information

TS 4.9

⏯ Playground Link

Repro here on TS Playground

💻 Code

type Polygon = string[][] | string[][][];

const p1: Polygon = [['1','1'], ['2','2'], ['3','1'], ['1','1']];
const p2: Polygon = [[['1','1'], ['2','2'], ['3','1'], ['1','1']], [['2','2'],['2.4','2.4'],['3.1']]];

p1.every(console.log); // it works. No complains.
p2.every(console.log); // it works. No complains.

const fn = (polygon: Polygon): void => {
  // .every complains with "this expression is not callable"
  if (polygon.every((p) => p.length === 2)) {
    //
  }
};

🙁 Actual behavior

TS throws an error.

🙂 Expected behavior

TS should not throw an error.

CC: @emilioSp

[MartinJohns]

It's working consistently. Your two variables are not actually typed Polygon because the assignment narrows the type. When you add an as Polygon behind your assignment it won't narrow and the behavior is the same.

[emilioSp]

Ok, I see, but why .every is not callable on union type?

[MartinJohns]

See #36390 and referenced issues. Or search for this expression is not callable union.

[typescript-bot]

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