Usage

isArray([]); // => true
isArray("hello"); // => false

Installation

CLI

npx atmx add helper is-array

Manually

Copy and paste the following method into @/utils/helpers/undefined.ts:

import type { StrictExtract } from "@/types/strict-extract.ts";

/**
* `Array.isArray` but with better type inference.
*
* @example
* isArray([]) // => true
* isArray('hello') // => false
*/
export const isArray = (() => Array.isArray)() as <Input>(
value: Input,
) => value is ExtractArray<Input>;

/**
* An absurdly complicated but accurate type for extracting Array types.
*
* It's like `Extract<T, any[]>` but better with edge cases.
*/
export type ExtractArray<T> = T extends any
? [StrictExtract<T, readonly any[]>] extends [readonly any[]]
? Extract<T, readonly any[]>
: [StrictExtract<T, any[]>] extends [any[]]
  ? Extract<T, any[]>
  : unknown[] extends T
    ? unknown[]
    : never
: never;