type-fest

import type {Except, Merge, Simplify} from 'type-fest'; interface User { id: string; name: string; email: string; createdAt: Date; updatedAt?: Date; } interface UserProfile { bio: string; website?: string; } // Create a new user type that excludes 'id' and 'createdAt' type NewUser = Except<User, 'id' | 'createdAt'>; // Merge the new user type with a profile to create a complete user type FullUser = Simplify<Merge<NewUser, UserProfile>>; const newUser: FullUser = { name: 'Alice Wonderland', email: 'alice@example.com', bio: 'Exploring type safety in Wonderland.', website: 'https://alice.example.com' }; console.log(newUser); // Demonstrating a common pattern with strict mode // Type-fest types are designed with strict mode in mind. // For example, if 'updatedAt' was not optional and not provided, // TypeScript would catch the missing property if strict: true is enabled. const partialUserUpdate: Partial<NewUser> = { name: 'Alice Smith' }; console.log(partialUserUpdate);