requireNonArray

function requireNonArray<T>(
  value: T | unknown[],
  message: string = "Expected a non-array value."
): T;

Array.isArray is the whole test, so an array from another frame counts and an array-like object — arguments, a NodeList, { length: 0 } — does not.

isX and nonX answer a question and never interrupt control flow; requireX and requireNonX hand the value back or throw. The scheme is explained in Validation conventions.

Parameters

Parameter	Type	Description
`value`	`T \\| unknown[]`	The value to validate.
`message` (optional) `= "Expected a non-array value."`	`string`	The message of the exception. A default is used when omitted.

Returns

T — the same value, with an array excluded from its type.

Throws

Exception	Condition
`IllegalArgumentException`	the value is an array.

Examples

What passes and what does not

requireNonArray("abc"); // => "abc"
requireNonArray({ length: 0 }); // => { length: 0 }
requireNonArray([]); // throws IllegalArgumentException
requireNonArray([1, 2, 3]); // throws IllegalArgumentException

Source

src/lang/base/requireNonArray.ts

23 September 2026

This documentation was generated with AI (Claude) from the library's source code.

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