custom-exception

library0.1.2jsnpmunverified

The `custom-exception` package, currently at version 0.1.2, provides a foundational utility for creating custom error classes within Node.js applications. It aims to simplify the process of defining structured, extensible error types beyond the standard JavaScript `Error` object. While still in early development, as indicated by its low version number, it offers a mechanism to differentiate application-specific errors programmatically. Its release cadence is likely irregular, given its nascent stage. Key differentiators typically include boilerplate reduction for custom error inheritance, properties like status codes, and improved stack trace handling, though specifics depend on the full API. Users should anticipate potential API changes as the library evolves towards a stable major release.

testing

npm install custom-exception

github ↗package ↗

INSTALL

IMPORT

SIG · CUSTOM-EXCEPTION

custom-exception

testingjavascriptv0.1.2

Install

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Import

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Disk

—

Pass rate

0/ 6

Env Coverage0 / 6

glibc

18–22

musl

18–22

Install & Compatibility

Where this runs

tested against v? · npm install

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

node 18–226 runs

build_error

glibc

node 18–226 runs

build_error

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

CustomError

✓ import { CustomError } from 'custom-exception';

✗ const { CustomError } = require('custom-exception');

The library primarily targets modern JavaScript environments. While CommonJS might work via transpilation, direct ESM import is recommended. The API is considered experimental in v0.1.2.

CustomError

✓ class MyError extends CustomError { /* ... */ }

✗ class MyError extends Error { /* ... */ } // Misses custom-exception's features

To leverage the library's features, extend the provided `CustomError` class instead of the native `Error`.

Demonstrates defining a custom error by extending `CustomError`, adding custom properties, and catching it with `instanceof` checks.

import { CustomError } from 'custom-exception'; /** * Define a custom application-specific error by extending CustomError. * This allows for adding custom properties like 'code' or 'data'. */ class NotFoundError extends CustomError { constructor(message: string, resourceId?: string) { super(message); this.name = 'NotFoundError'; this.statusCode = 404; // Custom property this.resourceId = resourceId; // Custom property // Restore prototype chain for 'instanceof' checks in transpiled environments Object.setPrototypeOf(this, NotFoundError.prototype); } } /** * A function that might throw our custom error. */ function getUser(userId: string) { if (userId === 'nonexistent') { throw new NotFoundError(`User with ID '${userId}' not found.`, userId); } return { id: userId, name: `User ${userId}` }; } try { const user = getUser('nonexistent'); console.log(user); } catch (error) { if (error instanceof NotFoundError) { console.error(`Error: ${error.name} - ${error.message} (Status: ${error.statusCode}, Resource: ${error.resourceId})`); } else if (error instanceof CustomError) { console.error(`Caught a generic CustomError: ${error.name} - ${error.message}`); } else if (error instanceof Error) { console.error(`Caught a standard Error: ${error.name} - ${error.message}`); } }

Debug

Known issues

breakingAs the package is at version 0.1.2, its API is considered unstable. Minor or patch releases may introduce breaking changes without prior deprecation warnings. Users should lock package versions and review changes upon upgrade.

fix

Pin your package version (e.g., `"custom-exception": "0.1.2"`) and manually review the changelog before upgrading to new minor or patch versions.

affects: <1.0.0

gotchaWhen extending `CustomError` in a transpiled environment (e.g., Babel, TypeScript targeting ES5/ES2015), you must explicitly call `Object.setPrototypeOf(this, MyCustomError.prototype)` in the constructor after `super()` to ensure `instanceof` checks work correctly.

fix

Add `Object.setPrototypeOf(this, MyCustomError.prototype);` to your custom error class constructor after `super(message);`.

affects: >=0.1.0

gotchaForgetting to set `this.name` in your custom error class constructor will result in the error name defaulting to 'CustomError' or 'Error' instead of your specific class name.

fix

Always set `this.name = 'MyCustomError';` in the constructor of your derived error class to ensure accurate error identification.

affects: >=0.1.0

Errors

Common errors & fixes

TypeError: Class constructor CustomError cannot be invoked without 'new'

Attempting to call `CustomError` or a derived class as a function instead of instantiating it with `new`.

fix

Always create instances of `CustomError` or its derivatives using `new`, e.g., `throw new CustomError('message');`.

MyCustomError is not an instance of CustomError

This typically occurs in transpiled environments where the prototype chain is not correctly re-established for custom error classes, preventing `instanceof` from working as expected.

fix

Ensure `Object.setPrototypeOf(this, MyCustomError.prototype);` is called in your custom error's constructor after `super()`.

Upgrade

Version history

0.1.2latest on npm

Audit

Dependencies

No dependency data recorded yet.

Agent activity

6 hits · last 30 days

node

Resources

githubhttps://github.com/Terran-Source/node-custom-exception ↗

packagehttps://www.npmjs.com/package/custom-exception ↗