how to append elements html via js code example

Example 1: javascript add div

<div id="new">
<p id="p1">Tutorix</p>
<p id="p2">Tutorialspoint</p>
</div>
<script>
   var tag = document.createElement("p");
   var text = document.createTextNode("Tutorix is the best e-learning platform");
   tag.appendChild(text);
   var element = document.getElementById("new");
   element.appendChild(tag);
</script>

Example 2: JavaScript append HTML

let app = document.querySelector('#app');
app.append('append() Text Demo');

console.log(app.textContent);