JSFiddle - React, Tailwind, and code Playground

HTML

<div class="topimage">
    <span id='close'>x</span>
</div>

CSS

.topimage{
    transition: opacity 1000ms;
}
.topimage.fadeOut{
    opacity: 0;
}

JavaScript

var close = document.querySelector("#close");

close.addEventListener('click', function(){
    var parent = this.parentNode;
    parent.classList.add('fadeOut');
    setTimeout(function(){
        parent.remove();
    }, 500);
});