JSFiddle - React, Tailwind, and code Playground

HTML

<div class="one">
</div>

<textarea id="mainContent"  onkeydown="TextareaAuto(this)" style="overflow:hidden">
    
</textarea>

CSS

.one{
    width: 100px;
    height: 30px;
    background: red;
}

textarea{ overflow: hidden;}

JavaScript

$('.one').hide();

$(function(){
    //hide show dive on enter press and on other keys hide div
$('#mainContent').on('keypress', function(e){
    if (e.which == 13) {
        e.preventDefault();
        $('.one').show();
    }
    else{
        $('.one').hide();
    }
});

    function TextareaAuto(o) {
	    o.style.height = "200px";
	    o.style.height = (2+o.scrollHeight)+"px";
    }
    
    
});