JSFiddle - React, Tailwind, and code Playground
HTML
<div contentEditable="true" id="con">
Este conteúdo pode ser editado.
</div>
<button onclick="capturarConteudo('con')">
CAPTURE
</button>
CSS
#con{
padding: 20px;
border-radius: 5px;
background-color: #eee;
border: 2px solid grey;
}
#con:focus{
outline:none;
border: 2px solid blue;
}
JavaScript
function capturarConteudo(id_container){
var c = document.querySelector("#"+id_container).innerHTML;
alert(c);
}