ReactDOM.render on class div ?

Question

Hi, i'm currently learning React and came to the subject of functional components and class components.
As in the example, a div with an id is used, i wanted to try the same thing on multiple div elements (placed in an index.html file) with a common class name.
Thing is, it doesn't work.
I want to understand why, how React work in those cases, and finally, how to do it.
Here's the code that i made :

class Ok extends React.Components {
render() {
return <h3>Bonjour !</h3>;
}
}

var hello = <Ok />;
ReactDOM.render(hello, document.getElementsByClassName('test'));

Thanks for your help ;-)

Answer 1

https://stackoverflow.com/questions/56789532/react-render-inside-class-tag-instead-id/56789835
ReactDOM.render() expect single element but with className you got array of elements, thats why is not working.

Answer 2

I see, thanks 👍