JSFiddle - React, Tailwind, and code Playground

by Marventus

HTML

<div id="mydiv">Some div</div>

CSS

html {
    height:3000px;
}
div {
    background:#ccf;
    display:none;
    height:100px;
    position:absolute;
    left:10%;
    margin-bottom:1000px;
    top:2000px;
    width:80%;
}
div.focus {
    display:block;
}

JavaScript

function scrollToDiv(id) {
    var id = $("#"+id);
    if( id.position().top + $(window).height() - $(window).scrollTop() > 0 )
        id.addClass("focus");
    else
        id.removeClass("focus");
        
}
$(window).scroll(function() {
    scrollToDiv("mydiv");
});