requireException
function requireException(value: unknown, message: string = "Expected an Exception."): Exception;
The library's own hierarchy only. A plain Error does not qualify, which is exactly what makes the check useful in a catch block that has to tell the two apart.
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
Exception — the same value, typed as an Exception.
Throws
Exception | Condition |
|---|---|
| the value is not an |
Examples
What passes and what does not
requireException(new IllegalArgumentException()); // => new IllegalArgumentException()
requireException(new Error()); // throws IllegalArgumentException
requireException({}); // throws IllegalArgumentException
See also
Source
23 September 2026
This documentation was generated with AI (Claude) from the library's source code.