isNonEmpty

Checks if an array is non-empty (has at least one element). null and undefined are treated as empty arrays and return false.

Available since v2.0.3

Import

import { isNonEmpty } from '@helpers4/array';
// or, from the all-in-one package (same code, one install):
import { isNonEmpty } from 'helpers4/array';

Signature

isNonEmpty<T>(value: readonly T[] | null | undefined): value is readonly [T, T]

Parameters

Parameter	Type	Description
value	readonly T[] | null | undefined	The array to check

Returns

value is readonly [T, T] — true if the array has at least one element; false for empty, null, or undefined

Examples

Check if an array has elements

Returns true for arrays with at least one element, regardless of the element values.

isNonEmpty([1, 2, 3]) // => true
isNonEmpty([null])    // => true  (null is still an element)
isNonEmpty([])        // => false

Safe first-element access with type narrowing

In the true branch, the type narrows to [T, …T[]], making arr[0] always defined.

function first<T>(arr: readonly T[]): T | undefined {
  if (isNonEmpty(arr)) return arr[0]; // arr[0] is T, not T | undefined
  return undefined;
}
first([1, 2]) // => 1
first([])     // => undefined

Name conflict

A helper named isNonEmpty also exists in @helpers4/object, @helpers4/string. If you need both in the same file, rename at import with as:

import { isNonEmpty as isNonEmpty4array } from '@helpers4/array';
import { isNonEmpty as isNonEmpty4object } from '@helpers4/object';
import { isNonEmpty as isNonEmpty4string } from '@helpers4/string';

See Name Conflicts for the full resolution guide.

Source

View source on GitHub