JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.1.0/jquery.min.js"></script>
<div id="textarea_container">

</div>
<button id="addTextArea">Adicionar Textarea</button>
<br>
<button id="getTextAreaLength">Pegar tamanho
</button>

JavaScript

var adicionou = false;
$('#addTextArea').click(function(){
		if(!adicionou)
    {
    	$('#textarea_container').append('<textarea id="textarea_1"></textarea>');
    }
});

$('#getTextAreaLength').click(function(){
	alert($('#textarea_1').val().length);
});