login.js

function loggedIn() {
  // ...
}

function requireAuth(nextState, replace) {
  if (!loggedIn()) {
    replace({
      pathname: '/login'
    })
  }
}

function routes() {
  return (
    <Route path="/" component={App}>
      <Route path="login" component={Login} />
      <Route path="logout" component={Logout} />
      <Route path="checkout" component={Checkout} onEnter={requireAuth} />
    </Route>
  );
}

thanks for sharing this,
I still wonder, what could be implementation for loggedIn, if there is a redux store;
in other words, how to make store avalilable for lookups within loggedIn function?

Thanks, and same question from me, How to make store available for lookups? or is there anyway to make getState() be available?

@Gera3dartist FYI, I tested it and it works for me.
https://stackoverflow.com/questions/35849970/accessing-redux-store-from-routes-set-up-via-react-router

But the code need to be change a bit.

export const getRoutes = (store) => {
	const authRequired = (nextState, replaceState) => {
		....
	};
	return (
		<Route path="/" component={App}>
			<Route path="signup" component={SignUp} onEnter={authRequired}/>
		</Route>
	);
};