requireLength
function requireLength(
value: unknown,
message: string = "Expected a valid array-like length."
): number;
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 |
|---|---|---|
|
| The value to validate. |
|
| The message of the exception. A default is used when omitted. |
Returns
number — the same value, typed as a valid array-like length.
Throws
Exception | Condition |
|---|---|
| the value is not a valid array-like length. |
Examples
What passes and what does not
requireLength(0); // => 0
requireLength(42); // => 42
requireLength(-1); // throws IllegalArgumentException
requireLength(1.5); // throws IllegalArgumentException
See also
Source
23 September 2026
This documentation was generated with AI (Claude) from the library's source code.