node-errors-helpers

⚠ Errors Helpers

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

Installation

Run npm install --save node-errors-helpers

Example

Simple usage of this lib.

const { createErrorClass, createErrorsList } = require('errors-helpers');

const SWError = createErrorClass(
  'RuntimeError',
  '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.

API

• createErrorClass(name, message, baseType) ⇒ CustomError
• createErrorsList(list, extend) ⇒ Object
• helpers
  • .getFullName(error) ⇒ String
  • .getObject(error) ⇒ Object
  • .getFullStack(error) ⇒ Array\<String>
  • .hasErrorClass(error, ErrorClass) ⇒ Boolean

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

CustomError

Any custom error has such constructor:

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

helpers.getFullName(error)

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

Returns: String

Param	Type	Description	Optional
error	CustomError	CustomError	no

helpers.getObject(error)

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

helpers.getFullStack(error)

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