<!DOCTYPE html>
<html>
<body>
<p id="myP">This is a paragraph.</p>
<select onchange="myFunction(this);" size="11">
<option>xx-small</option>
<option>x-small</option>
<option>small</option>
<option>medium</option>
<option>large</option>
<option>x-large</option>
<option>xx-large</option>
<option>100%</option>
<option>250%</option>
<option>2cm</option>
<option>100px</option>
</select>
<script>
function myFunction(selectTag) {
var listValue = selectTag.options[selectTag.selectedIndex].text;
document.getElementById("myP").style.fontSize = listValue;
}
</script>
</body>
</html>