Sort compare function with key accessor

sort.ts

type FilteredKeys<T, U> = { [P in keyof T]: T[P] extends U ? P : never }[keyof T]
  
const compare = <T>(fn: (x: T, y: T) => number) => <O extends object>(key: FilteredKeys<O, T>) => (
  a: O,
  b: O,
): number => {
  const valA = (a[key] as unknown) as T
  const valB = (b[key] as unknown) as T

  return fn(valA, valB)
}

export const compareStrings = compare<string>((a, b) => a.localeCompare(b))
export const compareDates = compare<Date>((a, b) => a.valueOf() - b.valueOf() )