const items = ['apple', 'banana', 'cherry', 'date'];  

const result = items
  .map(item => item.toUpperCase())
  .filter(item => item.length > 5)
  .reduce((acc, item, index) => {
    return acc + (index === 0 ? '' : '-') + item.slice(0, 3);
  }, '');

console.log(result);

const numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];

const result = numbers
  .filter(n => n % 2 === 0)
  .map(n => n * 2)
  .reduce((acc, curr, idx, arr) => {
    if (idx === arr.length - 1) {
      return (acc + curr) / arr.length;
    }
    return acc + curr;
  }, 0);

console.log(result);

const teams = [
  { name: 'Warriors', players: ['Curry', 'Thompson'] },
  { name: 'Lakers', players: ['James', 'Davis'] }
];

const newTeams = JSON.parse(JSON.stringify(teams));
newTeams[0].players.push('Green');

const shallowCopy = [...teams];
shallowCopy[1].name = 'Clippers';

const freezeTest = Object.freeze({nested: {value: 42}});
freezeTest.nested.value = 100;

console.log(teams[1].name, teams[0].players.length, freezeTest.nested.value);

let x = 5;

function foo() {
  console.log(x);
  let x = 10;
  console.log(x);
}

foo();

const fruits = ['apple', 'banana', 'cherry'];
const newFruits = [...fruits];

newFruits.push('date');

const user = { name: 'Taylor', age: 30 };
const updatedUser = { ...user, age: 31 };

user.city = 'Seattle';

console.log(fruits.length, newFruits.length, user.city, updatedUser.city);