jQuery Selectors

<!DOCTYPE html>
<html>
<head>
    <script src="https://code.jquery.com/jquery-3.7.1.min.js"></script>
    <style>
        body { font-family: sans-serif; padding: 20px; background: #f8fafc; }
        .demo-area { background: white; padding: 20px; border: 1px solid #cbd5e1; border-radius: 8px; margin-bottom: 15px; }
        .sorot { background-color: #fca311 !important; color: #0d2e5c !important; font-weight: bold; padding: 3px 6px; border-radius: 4px; }
        button { background: #00758f; color: white; border: none; padding: 8px 14px; border-radius: 6px; cursor: pointer; margin: 4px; }
    </style>
</head>
<body>
    <h3>Laboratorium Selektor jQuery</h3>
    <div class="demo-area">
        <h4 id="judulUtama">Judul Halaman (#judulUtama)</h4>
        <p class="paragraf-info">Paragraf 1 (.paragraf-info)</p>
        <p class="paragraf-info">Paragraf 2 (.paragraf-info)</p>
        <p>Paragraf Biasa Tanpa Kelas</p>
    </div>

    <div>
        <button id="btnSemua">Pilih Semua ('*')</button>
        <button id="btnId">Pilih ID ('#judulUtama')</button>
        <button id="btnKelas">Pilih Kelas ('.paragraf-info')</button>
        <button id="btnReset" style="background:#64748b;">Bersihkan</button>
    </div>

    <script>
        $(document).ready(function() {
            function clear() { $('.demo-area *').removeClass('sorot'); }
            $('#btnSemua').click(function() { clear(); $('.demo-area *').addClass('sorot'); });
            $('#btnId').click(function() { clear(); $('#judulUtama').addClass('sorot'); });
            $('#btnKelas').click(function() { clear(); $('.paragraf-info').addClass('sorot'); });
            $('#btnReset').click(function() { clear(); });
        });
    </script>
</body>
</html>