>
> (add-hook 'js-mode-hook
>           (lambda ()
>             (setq-local comment-start "{/* ")
>             (setq-local comment-end   " */}")))
>

It now works for JSX, but breaks on regular JS code (inside the same .jsx
file):

const [open, setOpen] = React.useState(false);
const [options, setOptions] = React.useState([]);

becomes:

{/* const [open, setOpen] = React.useState(false); */}
{/* const [options, setOptions] = React.useState([]); */}

Would there be a way for the comment function to know whether it is in a
JSX block or not, and act accordingly?