JSFiddle - React, Tailwind, and code Playground

HTML

<button onclick="myFunction()">Button</button>

<div class="content">
Content of element
</div>

CSS

.content {
    width: 80%;
    padding: 10%
    text-align: center;
    background-color: lightblue;
    margin-top:20px;
}

JavaScript

window.myFunction = function () {
    var x = document.getElementsByClassName('content');
    if (x.style.display === 'none') {
        x.style.display = 'block';
    } else {
        x.style.display = 'none';
    }
}