most-senior-developer.js

// kata - https://www.codewars.com/kata/582887f7d04efdaae3000090

function findSenior(list) {
  const results = new Set();
  let oldest = -Infinity;
  for (const person of list) {
    const { age } = person;
    if (age > oldest) {
      oldest = age;
      results.clear();
      results.add(person);
    }
    if (age === oldest) {
      results.add(person);
    }
  }
  return [...results];
}

let list1 = [
  { firstName: 'Gabriel', lastName: 'X.', country: 'Monaco', continent: 'Europe', age: 49, language: 'PHP' },
  { firstName: 'Odval', lastName: 'F.', country: 'Mongolia', continent: 'Asia', age: 38, language: 'Python' },
  { firstName: 'Emilija', lastName: 'S.', country: 'Lithuania', continent: 'Europe', age: 19, language: 'Python' },
  { firstName: 'Sou', lastName: 'B.', country: 'Japan', continent: 'Asia', age: 49, language: 'PHP' },
];

let answer1 = [
  { firstName: 'Gabriel', lastName: 'X.', country: 'Monaco', continent: 'Europe', age: 49, language: 'PHP' },
  { firstName: 'Sou', lastName: 'B.', country: 'Japan', continent: 'Asia', age: 49, language: 'PHP' },
];

let list2 = [
  { firstName: 'Gabriel', lastName: 'X.', country: 'Monaco', continent: 'Europe', age: 49, language: 'PHP' },
  { firstName: 'Odval', lastName: 'F.', country: 'Mongolia', continent: 'Asia', age: 38, language: 'Python' },
  { firstName: 'Emilija', lastName: 'S.', country: 'Lithuania', continent: 'Europe', age: 19, language: 'Python' },
];

let answer2 = [{ firstName: 'Gabriel', lastName: 'X.', country: 'Monaco', continent: 'Europe', age: 49, language: 'PHP' }];

let list3 = [
  { firstName: 'Alexander', lastName: 'F.', country: 'Russia', continent: 'Europe', age: 89, language: 'Java' },
  { firstName: 'Fatima', lastName: 'K.', country: 'Saudi Arabia', continent: 'Asia', age: 21, language: 'Clojure' },
  { firstName: 'Mark', lastName: 'G.', country: 'Scotland', continent: 'Europe', age: 22, language: 'JavaScript' },
  { firstName: 'Nikola', lastName: 'H.', country: 'Serbia', continent: 'Europe', age: 29, language: 'Python' },
  { firstName: 'Jakub', lastName: 'I.', country: 'Slovakia', continent: 'Europe', age: 28, language: 'Java' },
  { firstName: 'Kseniya', lastName: 'T.', country: 'Belarus', continent: 'Europe', age: 89, language: 'JavaScript' },
  { firstName: 'Luka', lastName: 'J.', country: 'Slovenia', continent: 'Europe', age: 29, language: 'Clojure' },
  { firstName: 'Mariam', lastName: 'B.', country: 'Egypt', continent: 'Africa', age: 89, language: 'Python' },
];

let answer3 = [
  { firstName: 'Alexander', lastName: 'F.', country: 'Russia', continent: 'Europe', age: 89, language: 'Java' },
  { firstName: 'Kseniya', lastName: 'T.', country: 'Belarus', continent: 'Europe', age: 89, language: 'JavaScript' },
  { firstName: 'Mariam', lastName: 'B.', country: 'Egypt', continent: 'Africa', age: 89, language: 'Python' },
];

console.log(findSenior(list1), answer1);
console.log(findSenior(list2), answer2);
console.log(findSenior(list3), answer3);