JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.2/jquery.min.js"></script>
<div id="mydiv" style="font-size:16px;height:2.5em;line-height:2.5em;width:10em;background:orange;text-align:center;">
  hello world
</div>

<br>

<input type="text" id="input">
<button>
  change size
</button>

JavaScript

$('button').on('click', function(){
	
  var value = $('#input').val();
  
  $('#mydiv').css('font-size', value + 'px');
  
});