JSFiddle - React, Tailwind, and code Playground

HTML

<a href="#" class="menu active" onclick="changeClass()">test 1</a>
    <a href="#" class="menu" onclick="changeClass()">test 2</a>
    <a href="#" class="menu" onclick="changeClass()">test 3</a>

CSS

.menu { color:blue; }
.active { color:red; }

JavaScript

function changeClass() {
      document.getElementsByClassName('menu').classList.remove('active');
      this.className('menu active');
    }