Contoh Manipulasi Elemen HTML

<div id="id_ku">ini Konten Asli</div>
<button onclick="ubah()">Ubah</button>
<script type="text/javascript">
function ubah(){
    document.getElementById('id_ku').innerHTML = 'Diubah dengan JavaScript';
}
</script>

Sumber : http://www.developer-id.com/