JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/autosize.js/3.0.20/autosize.js"></script>
<form>
  <input type="text" placeholder="請輸入暱稱">
  <textarea></textarea>
  <button>送出</button>
</form>

CSS

*, *::before, *::after {
  box-sizing: border-box;
}

form {
  width: 300px; 
}

input,
textarea,
button {
  display: block;
  width: 100%;
  margin-top: 10px;
  font-size: 24px;
}

textarea {
  min-height: 88px;
}

JavaScript

const submit = document.querySelector('button');
const post = document.querySelector('textarea');

function prevent() {
	event.preventDefault();
}

submit.onclick = prevent;

autosize(post);