JSFiddle - React, Tailwind, and code Playground

HTML

<button id='btn'>Жми</button>

<div id='block'></div>

CSS

div:not(#block) {
    width: 250px;
    height: 50px;
    border: 1px black solid;
    margin: 2px;
    overflow-y: scroll;
}
span {
    color: red;
    display: none;
    font-size: 76px;
}

JavaScript

$('#btn').on('click', function() {
   $('<div><span>scroll</span><br><br><br></div>').appendTo('#block'); 
});



$('#block').on('mouseenter', 'div', function() {
    if($(this).data('on-scroll') == undefined) {
        $(this).data('on-scroll', true);

        $(this).scroll(function(data){
            $('span', this).css("display", "inline").fadeOut("slow");
            return false;
        });
    }
});