JSFiddle - React, Tailwind, and code Playground

HTML

<html>
<head>
<title>Contoh saja</title>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<script type="text/javascript">
	$(document).ready(function(){
  	$("#tombol").click(function(){
    var target = $("textarea[name=txt]");
    var code = "[code]  [/code]";
    
    target.text(code);
    })
  });
</script>
</head>
<body>
<button id="tombol">Click Me</button>
<textarea name="txt" cols="30" rows="10"></textarea>
</body>
</html>