.card::before { content: '★'; position: absolute; top: 10px; left: 10px;}
const items = document.querySelectorAll('.item');const isArray = Array.isArray(items);const canMap = typeof items.map === 'function';console.log(isArray, canMap);
const btn = document.querySelector('.btn');btn.dataset.id = '123';btn.dataset.userName = 'Alice';console.log(btn.getAttribute('data-user-name'));
.container { display: flex; align-content: space-between; flex-wrap: wrap; height: 300px;}
const str = 'JavaScript';const char1 = str[0];const char2 = str.charAt(0);str[0] = 'j';console.log(str[0], char1 === char2);
const numbers = [1, 2, 3, 4, 5];const even = numbers.every(n => n % 2 === 0);console.log(even);
.menu { list-style: none; padding: 0; margin: 0;}.menu li { display: inline-block; margin-right: 15px;}
const a = 5;const b = '5';const c = 5;console.log(a == b, a === c);
const word = 'JavaScript';const upper = word.toUpperCase();console.log(word, upper);
.button { padding: 10px 20px; border: 2px solid black; border-radius: 5px;}