JSFiddle - React, Tailwind, and code Playground

by huuzoo

HTML

<a href="#" onclick="classChange()">ボタン</a>
<div id="target" class="classNameBefore">class名によって背景を変えます</div>

CSS

.classNameBefore {
  background-color: red;
}

.classNameAfter {
  background-color: blue;
}

JavaScript

function classChange() {
  var target = document.getElementById("target");
  target.className = "classNameAfter";
}