requireNonLength

function requireNonLength<T>(
  value: T,
  message: string = "Expected a value that is not a valid array-like length."
): T;

A whole number from 0 up to Number.MAX_SAFE_INTEGER — the range a length property may hold.

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`	The value to validate.
`message` (optional) `= "Expected a value that is not a valid array-like length."`	`string`	The message of the exception. A default is used when omitted.

Returns

T — the same value, with a valid array-like length excluded from its type.

Throws

Exception	Condition
`IllegalArgumentException`	the value is a valid array-like length.

Examples

What passes and what does not

requireNonLength(-1); // => -1
requireNonLength(1.5); // => 1.5
requireNonLength(0); // throws IllegalArgumentException
requireNonLength(42); // throws IllegalArgumentException

Source

src/lang/base/requireNonLength.ts

23 September 2026

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

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