fejl

import { MakeErrorClass, NotFound } from 'fejl'; // 1. Create a custom error class with a default message and properties class InvalidConfigError extends MakeErrorClass( 'The configuration file is invalid', { infoUrl: 'https://example.com/error-info' } ) {} // 2. Demonstrate throwing and catching a custom error try { throw new InvalidConfigError('Custom message ignored'); } catch (err) { console.log(`Error Name: ${err.name}`); // InvalidConfigError console.log(`Error Message: ${err.message}`); // The configuration file is invalid (default message is used) console.log(`Error Info URL: ${err.infoUrl}`); // https://example.com/error-info console.log(`Is instance of InvalidConfigError? ${err instanceof InvalidConfigError}`); // true } // 3. Use a built-in HTTP error with static assertion class UserNotFoundError extends NotFound {} function getUserById(id) { const user = id === 1 ? { id: 1, name: 'Alice' } : null; // Use static assert to throw if 'user' is falsy UserNotFoundError.assert(user, `User with ID ${id} not found.`); return user; } try { getUserById(2); } catch (err) { console.log(`\nHTTP Error Name: ${err.name}`); // NotFound console.log(`HTTP Error Message: ${err.message}`); // User with ID 2 not found. console.log(`HTTP Status Code: ${err.statusCode}`); // 404 }