tree-topper.html

<div class="controls">
	<select name="toppers">
		<option value="⭐">⭐</option>
		<option value="👼">👼</option>
	</select>
</div>
...
<script>
	const topSelector = document.querySelector('select');
	const topper = document.querySelector('.topper');
	function handleChange() {
		topper.textContent = topSelector.value;
	}
	topSelector.addEventListener('change', handleChange);
</script>