@nick/is/non-empty-array

isNonEmptyArray

Signature

function isNonEmptyArray<T>(
  a: MaybeArray<T>,
  test?: Predicate<T>,
): a is NonEmptyArray<T>;

Checks if the given value is an array with at least one element 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 the value is an array with at least one element of the specific type (if a test predicate is provided), false otherwise.

Category

Indexed Collections

Examples

import { isNonEmptyArray } from "jsr:@nick/is/array";

console.log(isNonEmptyArray([])); // false
console.log(isNonEmptyArray([1, 2, 3])); // true
console.log(isNonEmptyArray({})); // false

import { isNonEmptyArray } from "jsr:@nick/is/array";
import { isString } from "jsr:@nick/is/string";
import { isNumber } from "jsr:@nick/is/number";
import { expectType } from "jsr:@nick/is/type/expect";

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

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

isNonEmptyArray

Signature

function isNonEmptyArray<T>(
  a: unknown,
  test?: Predicate<T>,
): a is NonEmptyArray<T>;

isNonEmptyArray

Signature

function isNonEmptyArray<T>(
  a: unknown,
  test?: Predicate<T>,
): a is NonEmptyArray<T>;

NonEmptyArray

Signature

export type NonEmptyArray<T = unknown> = [T, ...T[]];

Represents an array with 1 or more element of the specific type T.

Type Parameters

• T (default: unknown)

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Category

Indexed Collections