const numbers = [1, 2, 3];
numbers.push(4);
console.log(numbers);

const x = null;
const y = undefined;
const z = 0;

const result1 = x ?? 'default';
const result2 = y ?? 'default';
const result3 = z ?? 'default';

const combined = result1 ? result2 ? result3 : 'B' : 'C';

console.log(combined);

async function processValues() {
  try {
    console.log('Start');
    const a = await Promise.resolve('First');
    console.log(a);
    const b = await Promise.reject('Error');
    console.log(b);
    return 'Done';
  } catch (err) {
    console.log(err);
    return 'Recovered';
  } finally {
    console.log('Finally');
  }
}

processValues().then(result => console.log(result));

console.log(typeof null);
console.log(typeof undefined);
console.log(typeof {});
console.log(typeof []);

const a = [1, 2, 3];
const b = a.flatMap(x => [x, x * 2]);
console.log(b);

const json = '{"name":"Sarah","age":25,"active":true}';
const obj = JSON.parse(json);

obj.name = "Emma";
obj.age++;

const json2 = JSON.stringify(obj);
const obj2 = JSON.parse(json2);

obj.age = 100;

console.log(obj2.age);

const numbers = [1, 2, 3, 4, 5];

const pipeline = (...fns) => (value) => fns.reduce((acc, fn) => fn(acc), value);

const multiply = (x) => (y) => x * y;
const add = (x) => (y) => x + y;
const square = (x) => x * x;

const transform = pipeline(
  multiply(2),
  add(3),
  square
);

const result = numbers.map(transform);
console.log(result);

const multiplier = 3;

function createCounter() {
  let count = 0;
  const multiplier = 5;
  
  return function() {
    count++;
    return count * multiplier;
  };
}

const counter = createCounter();
console.log(counter());
console.log(counter());
console.log(multiplier);

const clothes = [ 'jacket', 't-shirt' ];
clothes.length = 0;
console.log(clothes[0]);

const weakMap = new WeakMap();
const obj1 = {};
const obj2 = { key: 'value' };

weakMap.set(obj1, obj2);

const result = weakMap.get(obj1).key.split('').reverse().join('');

console.log(result);