JSFiddle - React, Tailwind, and code Playground

HTML

<input id="mybutton" type="button" value="click me" /><br />

<label id="mylabel" for="mytextarea">Label A</label><textarea id="mytextarea">some stuff in here</textarea><br />  
    
<div id="test1"></div>

CSS

label { margin-right: 1em; }

JavaScript

$('#mybutton').click(function () {
    //store text area value
    var x = $('#mytextarea').val();
    //clear text area
    $('#mytextarea').val('');
    //enter textarea value into a new div
    var newdiv = $("<div></div>").html(x).attr('id', 'test');
    $('#test1').append(newdiv);
        
    //I have no idea what you are trying to do here
    var $label = $("#mylabel");
    var serializer = new XMLSerializer();
    //$label.text(serializer.serializeToString(newdiv));
});

/*
$('input:button').click(function () {
    var x = $('textarea').val();
    $('textarea').val('');
    var label = $("#<%= Label1.ClientID %>");
    var newdiv = $("<div></div>").html(x).attr('id', 'test');
    $('#test1').append(newdiv);
    var serializer = new XMLSerializer();
    label.text(serializer.serializeToString(newdiv));
    return false;
});
*/