JSFiddle - React, Tailwind, and code Playground

HTML

<textarea id="text"></textarea>
<div id="block">ОБАНА</div>

CSS

#block {
    display: none;
    background-color: #ccc;
    width: 60px;
}

JavaScript

function sec() {
    if (document.getElementById("text").value != "" && document.getElementById("text").value != "0") {
        document.getElementById("block").style.display = "block";
    }
    else {
        document.getElementById("block").style.display = "none";
    }
}
setInterval(sec, 500);