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interface User { type: 'user'; name: string; age: number; occupation: string; }
interface Admin { type: 'admin'; name: string; age: number; role: string; }
type PowerUser = Omit<User,'type'>&Omit<Admin,'type'>&{ type: 'powerUser' };
export type Person = User | Admin | PowerUser;
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: 'powerUser', name: 'Nikki Stone', age: 45, role: 'Moderator', occupation: 'Cat groomer' } ];
function isAdmin(person: Person): person is Admin { return person.type === 'admin'; }
function isUser(person: Person): person is User { return person.type === 'user'; }
function isPowerUser(person: Person): person is PowerUser { return person.type === 'powerUser'; }
export function logPerson(person: Person) { let additionalInformation: string = ''; if (isAdmin(person)) { additionalInformation = person.role; } if (isUser(person)) { additionalInformation = person.occupation; } if (isPowerUser(person)) { additionalInformation = `${person.role}, ${person.occupation}`; } console.log(`${person.name}, ${person.age}, ${additionalInformation}`); }
console.log('Admins:'); persons.filter(isAdmin).forEach(logPerson);
console.log();
console.log('Users:'); persons.filter(isUser).forEach(logPerson);
console.log();
console.log('Power users:'); persons.filter(isPowerUser).forEach(logPerson);
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