const weakMap = new WeakMap();
let obj = { name: 'Test' };
weakMap.set(obj, 'value');
obj = null;
console.log(weakMap.has(obj));

.container {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 20px;
}

const nums = [1, 2, 3, 4];
const doubled = nums.map(n => n * 2);
nums.length = 0;
console.log(doubled);

const obj = { x: 10, y: 20, z: 30 };
const { x, ...rest } = obj;
delete rest.y;
console.log(obj.y, rest.z);

.card {
  background-image: url('image.jpg');
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
}

const array = new Array(3);
const filled = array.fill(0);
const mapped = array.map(() => 1);
console.log(filled[0], mapped[0]);

const btn = document.querySelector('.btn');
btn.style.color = 'red';
btn.style.fontSize = '20px';
const styles = window.getComputedStyle(btn);
console.log(styles.color);

.container {
  columns: 3;
  column-gap: 20px;
}

const arr = [1, 2, 3];
const result = arr.reduceRight((acc, val) => acc + val, 0);
console.log(result);

const promise = Promise.reject('Error');
promise.catch(err => console.log('Caught'));
promise.catch(err => console.log('Again'));