err-code

What is err-code?

The 'err-code' npm package is a utility for creating error objects with custom error codes and properties. It simplifies the process of adding additional context to errors, making them more informative and easier to handle.

What are err-code's main functionalities?

Creating an error with a custom code

This feature allows you to create an error object with a custom error code. The custom code can be used to identify the error type more easily.

const createError = require('err-code');
const error = createError(new Error('Something went wrong'), 'E_CUSTOM');
console.log(error.code); // 'E_CUSTOM'

Adding custom properties to an error

This feature allows you to add custom properties to the error object, providing additional context and information about the error.

const createError = require('err-code');
const error = createError(new Error('Something went wrong'), 'E_CUSTOM', { detail: 'Additional error details' });
console.log(error.detail); // 'Additional error details'

Handling errors with custom codes

This feature demonstrates how to handle errors based on their custom codes, allowing for more specific error handling logic.

const createError = require('err-code');
try {
  throw createError(new Error('Something went wrong'), 'E_CUSTOM');
} catch (error) {
  if (error.code === 'E_CUSTOM') {
    console.error('Custom error occurred:', error.message);
  }
}

Other packages similar to err-code

create-error

The 'create-error' package provides a way to create custom error types with additional properties. It is similar to 'err-code' but focuses more on creating new error types rather than adding codes to existing errors.

custom-error-generator

The 'custom-error-generator' package allows you to generate custom error classes with additional properties. It is similar to 'err-code' but offers more flexibility in defining custom error classes.

verror

The 'verror' package is used for creating and manipulating chained errors. It provides more advanced features for error handling and is more complex compared to 'err-code'.

README

err-code

Create new error instances with a code and additional properties.

Installation

$ npm install err-code
// or
$ bower install err-code

The browser file is named index.umd.js which supports CommonJS, AMD and globals (errCode).

Why

I find myself doing this repeatedly:

var err = new Error('My message');
err.code = 'SOMECODE';
err.detail = 'Additional information about the error';
throw err;

Usage

Simple usage.

var errcode = require('err-code');

// fill error with message + code
throw errcode(new Error('My message'), 'ESOMECODE');
// fill error with message + code + props
throw errcode(new Error('My message'), 'ESOMECODE', { detail: 'Additional information about the error' });
// fill error with message + props
throw errcode(new Error('My message'), { detail: 'Additional information about the error' });

Pre-existing fields

If the passed Error already has a .code field, or fields specified in the third argument to errcode they will be overwritten, unless the fields are read only or otherwise throw during assignment in which case a new object will be created that shares a prototype chain with the original Error. The .stack and .message properties will be carried over from the original error and .code or any passed properties will be set on it.

Tests

$ npm test

License

Released under the MIT License.