How can I stop code from executing before?

<Router>
        <Routes>
          <Route path="/" component={Guard}>
            <Route path="/" component={Root} />
          </Route>

          <Route path="/login" component={Login} />
        </Routes>
</Router>

const Root: Component = () => {
  const ws = new WebSocket("...");
  ws.onmessage = e => {
    console.log(e);
  };

  return <h1>Root</h1>;
};