JSFiddle - React, Tailwind, and code Playground

by huuzoo

HTML

<input type="text"  id="textBox" onkeyup="textCheck()">
<p>文字数：<span id="countArea"></span></p>

JavaScript

function textCheck() {
	var textValue = document.getElementById("textBox").value;
  var textLength = textValue.length;
  document.getElementById("countArea").innerHTML = textLength;
}