JSFiddle - React, Tailwind, and code Playground

HTML

<textarea id="123"></textarea>
<div id="user-code"></div>

CSS

canvas{
    border: 1px solid black;
}

div{
    background-color:red;
    
}

JavaScript

$("#123").keyup(function(){
    if($(this).val() == ""){
       $('#user-code').css('display','none');
    }else{
       $('#user-code').css('display','block');
    }
   $("#user-code").html($(this).val());
   // $("#user-code").text($(this).val()); // If you want html code to be escaped
});