When you have an error-ish but what you really want is an Error

Usage no npm install needed!

<script type="module">
  import errorish from '';



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When you have an error-ish but what you really want is an Error.


npm install errorish

Use cases

There are three main use cases for Errorish:


See complete documentation.

  • Exception is an Error extending class with additional label, error and data fields.
  • Utils:
    • ensure ensures any is an Error, otherwise creating one -it can optionally include a normalization step, enabled by default.
    • normalize ensures an Error has a message, name, and stack properties -filling them if they're not defined.
    • capture runs Error.captureStackTrace if running in V8 to clean up the error stack trace.


See documentation for Exception.

Exception is an Error extending class that can store an identifying label, the source error that caused it and/or additional associated data. Exception also comes with several static and instance methods.

import { Exception } from 'errorish';

try {
  try {
    throw Error('Source');
  } catch(err) {
    // throws with label
    throw new Exception(['label', 'message'], err, { code: 401 });
} catch(err) {
  // throws without label
  throw new Exception(err.message, err, { code: 500 })



See documentation for ensure.

Ensure will return its first argument if an instance of Error is passed as such, otherwise instantiating and returning an Exception.

import { ensure } from 'errorish';

ensure('foo'); // Error: foo
ensure(Error('foo')); // Error: foo
ensure({ message: 'foo' }); // Error: foo


See documentation for normalize.

Normalization fills an error's message, name, and stack property when empty. It's performed by default by ensure, but it can also be run independently.

import { normalize } from 'errorish';

normalize(Error()); // Error: An error occurred
normalize(Error(), { message: 'Foo bar' }); // Error: Foo bar


See documentation for capture.

Captures the stack trace on Node and Chromium browsers.

import { capture } from 'errorish';