A tiny library to create custom errors in JavaScript.

Usage no npm install needed!

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




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A tiny library to create custom errors in JavaScript.

:cloud: Installation

# Using npm
npm install --save err

# Using yarn
yarn add err

:clipboard: Example

const Err = require("err");

// Basic usage
let e1 = new Err("Some nasty stuff happened");
// => [Error: Some nasty stuff happened]

// Provide the error code
let e2 = new Err("Some nasty stuff happened", "NASTY_STUFF_HAPPENED");
// => {
//   [Error: Some nasty stuff happened]
// }

// Provide the error code and some data
let e3 = new Err("Some nasty stuff happened", "NASTY_STUFF_HAPPENED", {
    additional: "data"
// => {
//   [Error: Some nasty stuff happened]
//   additional: 'data'
// }

// Provide the error data (including the code as well)
let e4 = new Err("Some nasty stuff happened", {
    additional: "data"
// => {
//   [Error: Some nasty stuff happened]
//   additional: 'data'
// }

// Wrap an existing error
let existingError = new Error("Some nasty stuff happened");
let e5 = new Err(existingError, {
    additional: "data"
  , and: "some more data"
// => {
//   [Error: Some nasty stuff happened]
//   additional: 'data'
// , and: 'some more data'
// }

let e6 = new Err({
    message: "Something went really wrong!!!"
  , additional: "data"
  , and: "some more data"
// => {
//   [Error: Something went really wrong!!!]
//   additional: 'data'
// , and: 'some more data'
// }

let e7 = new Err("Invalid option '<option>'.", {
    option: "test"
// { [Error: Invalid option 'test'.] option: 'test' }

:question: Get Help

There are few ways to get help:

  1. Please post questions on Stack Overflow. You can open issues with questions, as long you add a link to your Stack Overflow question.
  2. For bug reports and feature requests, open issues. :bug:
  3. For direct and quick help, you can use Codementor. :rocket:

:memo: Documentation

Err(error, code, data)

Create a custom error object.


  • String|Error|Object error: The error message or an existing Error instance or the data object where the message is the error message.
  • String|Object code: The error code or the data object.
  • Object data: The data object (its fields will be appended to the Error object).


  • Error The custom Error instance.

:yum: How to contribute

Have an idea? Found a bug? See how to contribute.

:sparkling_heart: Support my projects

I open-source almost everything I can, and I try to reply to everyone needing help using these projects. Obviously, this takes time. You can integrate and use these projects in your applications for free! You can even change the source code and redistribute (even resell it).

However, if you get some profit from this or just want to encourage me to continue creating stuff, there are few ways you can do it:

  • Starring and sharing the projects you like :rocket:

  • Buy me a book—I love books! I will remember you after years if you buy me one. :grin: :book:

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  • Support me on Patreon—Set up a recurring monthly donation and you will get interesting news about what I'm doing (things that I don't share with everyone).

  • Bitcoin—You can send me bitcoins at this address (or scanning the code below): 1P9BRsmazNQcuyTxEqveUsnf5CERdq35V6

Thanks! :heart:

:dizzy: Where is this library used?

If you are using this library in one of your projects, add it in this list. :sparkles:

  • scrape-it
  • tilda
  • emoji-logger
  • @sphinxdoc/core
  • bloggify-adapter
  • python-env
  • image-parser
  • validated-base
  • find-file-in-dirs
  • @asserted/models
  • git-package-json
  • multithread-config
  • @ecosystem/config
  • mocha-ldjson
  • engine-comp-crud-errors
  • engine-composition-adapter
  • fs-repo-url
  • gh-fork-source
  • lwip2
  • validify
  • sphinxdoc
  • @gatsbydoc/core
  • simple-cached-firestore
  • payiota
  • stringify-env
  • scrape-it-plus
  • @slikts/scrape-it
  • do-task
  • check-params
  • love-you
  • @sphinxdoc/cli
  • trace-breaking-change
  • @reactant/react-router
  • @gatsbydoc/sphinx
  • @gatsbydoc/cli
  • vkbeautify-cli
  • dotstow
  • ts-gir
  • simple-cached-datastore
  • git-sync-all
  • @ecosystem/core
  • asrtd
  • hunarcourses

:scroll: License

MIT © Ionică Bizău