array

@nick/is/array

isArray

Signature

function isArray<T>(a: unknown, test?: Predicate<T>): a is T[];

Checks if the given value is an array, optionally verifying that each of its elements are of a specific type.

Parameters

Name	Info
it	The value to check.
test	The type guard to check the type of the array elements.

Returns

true if it is an array, and the predicate (if provided) is satisfied by each of its values. Otherwise, returns false.

Category

Indexed Collections

Examples

import { isArray, isNumber, isString } from "jsr:@nick/is";
import { expectType } from "jsr:@nick/is/type/expect";

const arr: unknown[] = ["a", "b", "c"];

if (isArray(arr, isString)) {
  console.log(arr, "is an array of strings");
  //           ^? const arr: string[]
  expectType<string[]>(arr);
} else if (isArray(arr, isNumber)) {
  console.log(arr, "is an array of numbers");
  //           ^? const arr: number[]
  expectType<number[]>(arr);
} else {
  console.log(arr, "is not an array of strings or numbers");
  //           ^? const arr: unknown[]
  expectType<unknown[]>(arr);
}