isException
function isException(value: unknown): value is 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 check. |
Returns
boolean — true when the value is an Exception; otherwise false.
In TypeScript the guard narrows value to Exception inside the branch.
Examples
What passes and what does not
isException(new IllegalArgumentException()); // => true
isException(new Error()); // => false
isException({}); // => false
isException(null); // => false
See also
Source
23 September 2026
This documentation was generated with AI (Claude) from the library's source code.