Error3 is an Error with extra powers. It has been designed to be extensible and easy to use. Though it has codes, message formatters and nested errors.

• Modern: designed for TypeScript and ES2019.
• IDE friendly: it's using classes and class fields to be inspectable for autosuggetion tools.
• i18n ready: formatter could produce localized messages with help of Intl API.
• Easy serialization and deserealization: good for network apps and JSON logging.
• Frontend caring: 0 dependencies, gzipped version is less then 1 KiB.

Table of Contents

• Install
• Usage
• Examples
• API

Install

• In node.js:

  npm i error3

• In browser:

  <script src="https://unpkg.com/error3@3/dist/error3.min.js"></script>

  CommonJS · UMD · ESM

  ⚠️ Remember about security! Add subresource integrity (SRI) checksum from checksum.txt.

Usage

Error3 suppose that you will create some base error class for your application or library and then use it as a parent for all your errors. Watch example in examples folder. Here it is interface realization:

import Error3 from 'error3'

class NotFoundErr extends Error3 {
  code = 'fs_not_found'

  format({filepath}) {
    return `File "${filepath}" not found`
  }
}

This is what it gives to us:

const error = new NotFoundErr({filepath: './index.js'});
error.toString() // -> "NotFoundErr: [#fs_not_found] File "./index.js" not found"
error.message // -> "File "./index.js" not found"
error.code // -> fs_not_found
error.details // -> {filepath: './index.js'}

The same error TypeScript implementation:

import Error3 from 'error3'

class NotFoundErr extends Error3<{filepath: string}, void> {
  code = 'fs_not_found'

  format({filepath}): string {
    return `File "${filepath}" not found`
  }
}

JSON serialization

Calling Error3#toJSON() on Error3 instance returns an object with properties code, message, details, and errors. Example output:

{
  "code": "fs_not_found",
  "message": "File \"./index.js\" not found",
  "details": {
    "filepath": "./index.js"
  },
  "errors": []
}

Examples

• HTTP errors JS · TS
• FileSystem errors JS · TS
• Localized I18n error messages JS · TS

API

Error3()

(details:object = {}, errors:Error[] = []) -> Error3

abstract. Both of Error3 constructor arguments are optional. The resposibility of ancestor class is to implement proper interface and pass details object and errors list into super() call.

details is using to describe error with JS primitives. Though it could be sent via network to frontend, db, or ELK without extra parsing as it should be done with regular Error instance.

TS Interface

abstract class Error3<Details, Errors> extends Error implements IError3 {
  public readonly code: string|number
  public readonly name: string
  public readonly details: object
  public readonly errors: Error[]

  constructor(details: Details, errors: Errors) {}
  abstract format(detials: Details, errors: Errors): string
}

Example

const error = new UserMissed(
  {userId: 1}, [new Error('Collection removed')]
);

error.code // -> user_missed
error.message // -> User #1 not loaded
error.details // -> {userId: 1}
error.errors // -> [Error('Collection removed')]

Error#code

string|number

Error code should be a string or a number. It could be defined using class fields syntax:

class HttpNotFound extends HttpError {
  code = 404
}

Error3#format()

(details: object, errors: Error[]) -> string

abstract. Creates formatted message string from details and other errors. This method is calling from Error3 constrcutor to define message property.

JS

class PortInUse extends Error3 {
  format({port}) {
    return `Port ${port} is already in use`
  }
}

TS

class PortInUse extends Error3<{port: string|number}, void> {
  format({port}): string {
    return `Port ${port} is already in use`
  }
}

Error3#toJSON()

Wrapper of Error3#valueOf. It's created to be used by JSON.stringify().

Error3#valueOf()

() -> PlainError

This method realizes Object#valueOf() behavior and returns plain error object containing properties: code, message, details and errors.

PlainError{}

{
  code: string|number,
  message: string,
  details: object,
  errors: PlainError[],
}

It is a result of Error3#valueOf() call.

License

MIT © Rumkin