JSFiddle - React, Tailwind, and code Playground

HTML

<div class="hui"></div>
 <div class="zalupa"></div>

CSS

.hui{
    width:100px;
    height:100px;
    background:green;
}
.zalupa{
    width:50px;
    height:50px;
    background:red;
    display:none;
}
.display-zalupa {
    display:block;
}

JavaScript

$(document).ready(function() {
    $(document).on('click',function(e){
        e.stopPropagation();
        if (e.target.className == 'hui') {
            $('.zalupa').addClass('display-zalupa');
            } else {
            $('.zalupa').removeClass('display-zalupa');
            
        }      
    })
});