With regard to React

Question

I have a question about react, i wanted to change the content of the page by clicking, but the site recognizes only as Object.

Function

import React from 'react';   

//funções 
export  function botao2(){
    document.querySelector('.CassandraText').innerHTML = 'Downloading Cassandra';
    document.querySelector('.resumo').innerHTML = <h3>Latest Beta Version</h3>;
    console.log('clicado');
}

The button that calls the function

<button onClick={botao2}> 
    Download Cassandra
</button>

In case I was trying to open the <h3>, but when I send to component, he appears as object.

Answer 1

You have to give a studied how it works React, the way to change screens, variables, etc. Really before entering the world React give a studied in html, javascript and css at least the basic not to get lost in it.

When creating a component in React to change contents follows a minimum example:

function App() {
  const [nome, setNome] = React.useState('Inicial');
  return (
    <div>
      <h3>{nome}</h3>
      <button
          onClick={e => 
            setNome('Alterado com sucesso')}
       >Alterar</button>
    </div>
  )
}

ReactDOM.render( <App/> , document.getElementById('root'));

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.8.3/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.8.3/umd/react-dom.production.min.js"></script>
<div id="root">Carregando ...</div>

And so begins to use and the central idea of how to change page contents.