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);

for (var i =0; i < 10; i++){
 setTimeout(function (){
  console.log(i);
 }, 0);
}

const x = 0.1 + 0.2;
const y = 0.3;

console.log(x === y);
console.log(x.toFixed(1) === y.toFixed(1));
console.log(+x.toFixed(1) === +y.toFixed(1));

const num = 42;
console.log(num.toString(2));
console.log(parseInt('101010', 2));

const x = 5;
const y = 10;

const result = `${x + y}`;
const nested = `Value: ${`${x}` + `${y}`}`;
const expr = `${x}${y}`;

console.log(result);
console.log(nested);
console.log(expr);
console.log(typeof result);

const obj = Object.seal({ a: 1, b: { c: 2 } });
obj.a = 10;
obj.b.c = 20;
obj.d = 30;
delete obj.a;

const frozen = Object.freeze({ x: 5, y: { z: 10 } });
frozen.x = 50;
frozen.y.z = 100;
delete frozen.y;

console.log(obj.a, obj.b.c, obj.d, frozen.x, frozen.y.z);