Intl.Collator#compare method type does not match spec

[thw0rted]

⚙ Compilation target

ES2022

⚙ Library

N/A

Missing / Incorrect Definition

The Intl.Collator object has a compare method which is declared as compare(x: string, y: string): number; but according to the relevant spec is actually get compare(): (this: void, x: string, y: string) => number. Importantly, the spec states that

The returned function is bound to collator so that it can be passed directly to Array.prototype.sort or other functions

Sample Code

I'm having trouble putting together a Playground example that cares about the difference (which is admittedly subtle!) but it's the cause of typescript-eslint/typescript-eslint#7098

Documentation Link

Collator#compare spec
MDN docs on compare method

[ahsansheikh94]

Hi! I'd like to start working on this issue and submit a PR. Let me know if there's anything I should be aware of before I begin.

[bdpartridge]

One related issue with the current type declaration is that it only accepts strings, but the spec actually indicates that the values are coerced to strings, so all value types should be allowed. This is confirmed by the actual implemented behavior (in latest Chrome at least). Should the declaration be updated to reflect this too?

[RyanCavanaugh]

Braeden Partridge (@bdpartridge) no, otherwise by that logic Math.max("hello", "world") would be valid because its inputs are also coerced to string

[bdpartridge]

Ryan Cavanaugh (@RyanCavanaugh) Good point. Since the string coercion might be surprising, it's probably best to just stick with what's intended.

[RyanCavanaugh]

Intl.Collator#compare is a bound function in the platform: Edge 153 returns the same comparator value and it works when called with an undefined receiver. TypeScript 6.0.3 and current native 7.1.0-dev.20260918.1 still allow replacing collator.compare, but the declaration should model it as a readonly function-valued property with this: void.