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0.2.0 • Public • Published

⚠ Errors Helpers Build Status

This library helps with error handling in Node.

It provides following API:

  • Generators API
    • Custom error creation (with inheritance and chaining)
    • Creates lists of errors from simple key-value objects
  • Helpers API
    • Getting iterable object from error instance
    • Getting full name for inherited error instance
    • Getting array of stacks for an error chain
    • Detecting if there is an error of particular error class in the chain


Run npm install --save node-errors-helpers


Simple usage of this lib.

const { createErrorClass, createErrorsList } = require('errors-helpers');
const SWError = createErrorClass(
  'Runtime error',
  Error // parent error class, optional
const StarWarsErrors = createErrorsList({
  'NO_LUKE': 'No Luke Skywalker!',
  'NO_DARTH': 'No Darth Vader!',
  'YOUR_FATHER': 'I am you father, Luke!',
}, SWError);
throw new SWError();
throw new StarWarsErrors.YOUR_FATHER({ location: 'Bespin' });
throw new StarWarsErrors.NO_LUKE({ far: 'away' }, causedByError /* some generated or catched error */);

More examples.


createErrorClass(name, message, baseType))

Creates error class with the name provided, that will throw error with message. When baseType class provided, new error class will be extending base one, if not Error class is extended. Each error generated with this helper will have specific structure and constructor.

Returns: CustomError

Param Type Description Optional
name String Name the for class to generate. no
message String The message calss instance will be thrown with. no
baseType String Class to extend. If not provided Error class is extended. yes


Any custom error has such constructor:

  const err = new CustomError(data = null, causedBy = null);
  // err.causedBy

Created error class will throw error instance with message provided in class constructor. Field data has any type. So you can pass there everything.

You can pass an error as second param and it will be saved as cause of current error. See examples for more information.

createErrorsList(list, extend)

Generates object of errors from object of definitions. If no extend class provided error classes are extended from Error.

Object sample:

  'SOME_ERROR_CODE': 'Message that will be shown.',
  'ANOTHER_ERROR': 'Another message %)'

Returns: Object (key - code, value - Error)

Param Type Description Optional
list Object Object that define errors. no
extend AnyErrorType Class that all generated errors will extend. yes


Returns full name of error. Concats all parent classes names with ..

Returns: String

Param Type Description Optional
error CustomError CustomError no


Retruns iterable error data object.

For better errors representation in JSON format.

Returns: Object { name, stack, message, data, causedBy }

Param Type Description Optional
error CustomError CustomError no


Recursively gets stacks from causedBy errors and return Array of them.

Returns: Array\<String>

Param Type Description Optional
error CustomError CustomError no

helpers.hasErrorClass(error, ErrorClass)

Looks for ErrorClass in error. Recursivly looks in causedBy fields. Returns true if an instance of ErrorClass is found, false otherwise.

Returns: Boolean

Param Type Description Optional
error CustomError Where to look for class. no
ErrorClass AnotherCustomError What class to look for. no



npm i node-errors-helpers

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