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

const util = require('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.

const util = require('node:util');
const obj = { name: 'Error', message: 'an error occurred' };

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