<script> 
function changeColor() {
  const guoguo = document.getElementById('guoguo');
  guoguo.style.color = 'red';
}
function appendElement() {
  const keke = document.createElement('p');
  const text = document.createTextNode('科科真可爱');
  keke.appendChild(text);
  document.body.appendChild(keke);
}
</script>
<p id="guoguo">果果真可爱</p>
<button onclick="changeColor()">color</button>
<button onclick="appendElement()">append</button>