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isError - util - Node documentation
function isError

Usage in Deno

import { isError } from "node:util";
isError(object: unknown): object is Error
Deprecated

Since v4.0.0 - Use types.isNativeError instead.

Returns true if the given object is an Error. Otherwise, returns false.

import util from 'node:util';

util.isError(new Error());
// Returns: true
util.isError(new TypeError());
// Returns: true
util.isError({ name: 'Error', message: 'an error occurred' });
// Returns: false

This method relies on Object.prototype.toString() behavior. It is possible to obtain an incorrect result when the object argument manipulates @@toStringTag.

import util from 'node:util';
const obj = { name: 'Error', message: 'an error occurred' };

util.isError(obj);
// Returns: false
obj[Symbol.toStringTag] = 'Error';
util.isError(obj);
// Returns: true

Parameters

object: unknown

Return Type

object is Error