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interface User { type: 'user'; name: string; age: number; occupation: string; }
interface Admin { type: 'admin'; name: string; age: number; role: string; }
export type Person = User | Admin;
export const persons: Person[] = [ { type: 'user', name: 'Max Mustermann', age: 25, occupation: 'Chimney sweep' }, { type: 'admin', name: 'Jane Doe', age: 32, role: 'Administrator' }, { type: 'user', name: 'Kate Müller', age: 23, occupation: 'Astronaut' }, { type: 'admin', name: 'Bruce Willis', age: 64, role: 'World saver' }, { type: 'user', name: 'Wilson', age: 23, occupation: 'Ball' }, { type: 'admin', name: 'Agent Smith', age: 23, role: 'Anti-virus engineer' } ];
export function logPerson(person: Person) { console.log( ` - ${person.name}, ${person.age}, ${person.type === 'admin' ? person.role : person.occupation}` ); }
export function getObjectKeys<T>(obj:T){ return Object.keys(obj) as (keyof T)[] }
export function filterPersons(persons: Person[], personType: User['type'], criteria: Partial<Omit<User,'type'>>):User[]; export function filterPersons(persons: Person[], personType: Admin['type'], criteria: Partial<Omit<Admin,'type'>>):Admin[]; export function filterPersons(persons: Person[], personType: Person['type'], criteria: Partial<Person>):Person[]{ return persons .filter((person) => person.type === personType) .filter((person) => { let criteriaKeys = getObjectKeys(criteria); return criteriaKeys.every((fieldName) => { return person[fieldName] === criteria[fieldName]; }); }); }
export const usersOfAge23 = filterPersons(persons, 'user', { age: 23 }); export const adminsOfAge23 = filterPersons(persons, 'admin', { age: 23 });
console.log('Users of age 23:'); usersOfAge23.forEach(logPerson);
console.log();
console.log('Admins of age 23:'); adminsOfAge23.forEach(logPerson);
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