JSFiddle - React, Tailwind, and code Playground

HTML

<div id="mainDiv">
    <a id="toggleLink" href="#" rel="hidden">Click To Show</a>
</div>
<div id="toggleDiv">
    Hi!
</div>

CSS

#toggleDiv
{
    height: 200px;
    width: 200px;
    background: #BADA55;    
}

JavaScript

$(function () {
    if ($('#toggleLink').attr('rel') == 'hidden') {
        $('#toggleDiv').hide();
        $('#toggleDiv').fadeIn( 1500 );
    }
    else {
        $('#toggleDiv').show(); 
        $('#toggleDiv').fadeIn( 1500 );
    }
    $('#mainDiv a').on('click', function (evt) {
        evt.preventDefault();
        $('#toggleDiv').toggle();
        $('#toggleDiv').fadeIn( 1500 );
    });
});