@isdk/common-error

A lightweight, extensible error handling library for TypeScript and JavaScript projects. It provides a BaseError class that makes it easy to create custom, structured error types with support for error codes and additional metadata.

This library is built upon abstract-error.

Features

• Extensible: Easily create your own custom error classes by extending BaseError.
• Structured Errors: Attach error codes and custom data to your error objects for better error handling and logging.
• Pre-defined Errors: Comes with a set of common error types like NotFoundError, AlreadyExistsError, NotImplementationError, and AbortError.
• JSON Serialization: Convert error objects to and from JSON for easy transport over networks or for logging purposes.
• TypeScript Support: Written in TypeScript, with full type definitions.

Installation

Using npm:

npm install @isdk/common-error

Using yarn:

yarn add @isdk/common-error

Usage

Creating a Custom Error

You can easily create your own error classes by extending BaseError.

import { BaseError } from '@isdk/common-error';

class MyCustomError extends BaseError {
  constructor(message: string, public customData: { reason: string }) {
    super(message, 'MyCustomErrorCode'); // message and error code
    this.data = customData;
  }
}

try {
  throw new MyCustomError('Something went wrong!', { reason: 'internal failure' });
} catch (error) {
  if (error instanceof MyCustomError) {
    console.error(error.toJSON());
    // {
    //   name: 'MyCustomError',
    //   code: 'MyCustomErrorCode',
    //   data: { reason: 'internal failure' },
    //   error: 'Something went wrong!',
    //   stack: '...'
    // }
  }
}

Using Pre-defined Errors

The library includes several common error types out of the box.

import { NotFoundError, AlreadyExistsError, NotImplementationError, AbortError } from '@isdk/common-error';

// NotFoundError
try {
  throw new NotFoundError('User');
} catch (e) {
  // e.message will be "Could not find User."
  // e.code will be 404
}

// AlreadyExistsError
try {
  throw new AlreadyExistsError('Project');
} catch (e) {
  // e.message will be "The Project already exists."
  // e.code will be 409
}

// NotImplementationError
try {
  throw new NotImplementationError();
} catch (e) {
  // e.message will be "Not Implementation."
  // e.code will be 501
}

// AbortError
try {
  throw new AbortError('data processing');
} catch (e) {
  // e.message will be "The operation was aborted for data processing."
  // e.code will be 499
}

API Reference

BaseError

The core class of the library.

new BaseError(message: string, code?: ErrorCodeType, name?: string | Record<string, any>)

• message: The error message.
• code (optional): An error code (string or number). Defaults to the class name.
• name (optional): The error name. Can also be an object to assign additional properties to the error instance.

error.toJSON()

Returns a serializable JSON object representing the error.

static BaseError.fromJSON(json)

Creates a new error instance from a JSON representation. This is the reverse of toJSON() and is useful for deserializing errors.

• json: A JSON object, typically from a serialized error.

import { NotFoundError } from '@isdk/common-error';

const originalError = new NotFoundError('thing');
const json = originalError.toJSON();

// Deserialize the error
const newError = NotFoundError.fromJSON(json);

console.log(newError instanceof NotFoundError); // true
console.log(newError.message); // 'Could not find thing.'

static BaseError.create({error: message, code?, name?, data?})

Static method to create a new instance of the error class.

const err = BaseError.create({error: 'hello message', code: ErrorCode.NotFound});
// err is an instance of BaseError

static BaseError.createErrorClass(aType: string, aErrorCode?: number|string, ParentErrorClass?: typeof BaseError)

Static method to dynamically create a new Error class that inherits from ParentErrorClass (which defaults to BaseError).

const DatabaseError = BaseError.createErrorClass('DatabaseError', 'DB_ERROR');
const dbErr = new DatabaseError('Connection failed');
console.log(dbErr.name); // 'DatabaseError'
console.log(dbErr.code); // 'DB_ERROR'

Pre-defined Error Classes

All pre-defined error classes inherit from CommonError, which itself inherits from BaseError.

• CommonError: A general-purpose error class.
• NotImplementationError: For features that are not yet implemented. (Code: 501)
• NotFoundError: When a resource is not found. (Code: 404)
• AlreadyExistsError: When a resource already exists. (Code: 409)
• AbortError: When an operation is aborted. (Code: 499)

Helper Functions

createError(message: string, name?: string, status?: ErrorCodeType)

Creates and returns an error instance. It will try to pick the most appropriate error class based on the status code.

const err = createError('Could not find it.', undefined, ErrorCode.NotFound);
// err is an instance of NotFoundError

throwError(message: string, name?: string, status?: ErrorCodeType)

Creates and immediately throws an error.

try {
  throwError('Could not find it.', undefined, ErrorCode.NotFound);
} catch (e) {
  // e is an instance of NotFoundError
}

ErrorCode

An enum of common HTTP status codes used as error codes.

import { ErrorCode } from '@isdk/common-error';

console.log(ErrorCode.NotFound); // 404
console.log(ErrorCode.InternalError); // 500

Contributing

Contributions are welcome! Please open an issue or submit a pull request.

License

This project is licensed under the MIT License.