1) You’re missing a closing bracket on the ReactDOM
line:
ReactDOM.render(<Main />, document.getElementById('root'));
2) You need to call the function for it to work
vanilla_JS()
In this working example instead of logging to the console I’m returning a string:
function Main() {
const vanilla_JS = function() { return 'testing'; }
return (
<main>
<div>{vanilla_JS()}</div>
</main>
);
}
ReactDOM.render(<Main />, document.getElementById('root'));
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.8.4/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.8.4/umd/react-dom.production.min.js"></script>
<div id="root"></div>
solved How to add function in JSX?