JSFiddle - React, Tailwind, and code Playground

HTML

<h2> Titulo </h2>
Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do

<h2> OUTRO TITULO 1</h2>
Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do

<h2> OUTRO TITULO 2</h2>
Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do

<br/>
<button onclick="mostra();">Mostra lista</button>
<ul id="lista" />

CSS

h2
{
    cursor: pointer;
}

JavaScript

var headers = document.getElementsByTagName('h2');
for (var i = 0; i < headers.length; i++) {
    headers[i].onclick = armazena;
}

var titulos = [];

function armazena() {
    titulos.push(this);
}

function mostra() {
    var lista = document.getElementById('lista');
    lista.innerHTML = '';
    for (var i = 0; i < titulos.length; i++) {
        var el = document.createElement('li');
        el.innerHTML = titulos[i].innerHTML;
        lista.appendChild(el);
    }
}