❗️Что будет на выходе:

const company = {
  name: 'TechCorp',
  departments: {
    engineering: {
      head: { name: 'Alice', contact: null },
      staff: 50
    },
    marketing: null
  }
};

const engineeringContact = company.departments.engineering.head.contact;
const marketingHead = company.departments.marketing?.head?.name;
const financeStaff = company?.departments?.finance?.staff ?? 'Not available';

console.log(`${engineeringContact} - ${marketingHead} - ${financeStaff}`);

Ответ:
null - undefined -Not available

JavaScript test | #JavaScript