text: 
  var i, copy;
  var employees = [
    { name: 'John', age: 35, qualifications: ['React'] },
    { name: 'Bill', age: 45 },
    { name: 'Amy', age: 27 },
    { name: 'Ivan', age: 27, qualifications: ['React', 'TypeScript']}
  ];
  
  var person1 = {}; // prototyple
  person1.name = 'Petar';
  person1.age = 30;
  person1.qualifications = ['javascript', 'React', 'Vue.js']
  var person2 = new Object(); // pseudo-classical
  person2.name = 'Dimitar';
  person2.age = 40;
  person2.qualifications = ['C++', '.NET'];
  
  var person3 = Object.create(Object.prototype, {
    name: {
      value: 'Stefan', writable: true, enumerable: true, configurable: true
    },
    age: {
      value: 45, writable: true, enumerable: true, configurable: true
    },
    qualifications: {
      value: ['javascript', 'React 16', 'TDD'], writable: true, enumerable: true, configurable: true
    },
  });
  
  employees.push(person1, person2, person3);
  
  // console.log(employees);
  
  // Shallow copy
  var copy = employees.slice(0);// shallow copy
  console.log('Same?', employees === copy);
  console.log('Sahllow copy?: ', employees[0] === copy[0])
  
  // Deep copy
  var deepCopy = JSON.parse(JSON.stringify(employees));// deep copy
  // console.log(deepCopy)
  console.log('Same?', employees === deepCopy);
  console.log('Sahllow copy?: ', employees[0] === deepCopy[0]);
  
  // every
  const isQualified = (e) => e.qualifications && e.qualifications.length && e.qualifications.length > 0;
  console.log('Are all employees qualified?: ', 
    employees.every(isQualified))
  
  //some
  const isReactQualified = e =>
    isQualified(e) && e.qualifications.some(
      qual => qual.toLocaleLowerCase().includes('react'));
  console.log('Is some employee React qualified?: ', employees.some(isReactQualified))
  
  // filter
  // console.log('which employees are React qualified?: ', employees.filter(isReactQualified))
  
  // map
  console.log('What qualifications React employees posess?: ', 
    employees.filter(isReactQualified)
      .map(e => e.qualifications)
  );
  
  // reduce
  
  quallifications = employees.filter(isReactQualified)
    .map(e => e.qualifications)
    .reduce((acc, qa) => acc.concat(qa), []);
  
  qualSet = new Set(quallifications);
  console.log('What qualifications React employees posess?: ', [...qualSet]);
  
  
  
  
  
  