foo-shorter.js

render([
    [{path: "/", component: App},
      [{path: "about", component: About}],
      [{path: "users", component: Users},
        [{path: "/user/:userId", component: User}]
      ],
      [{path: "*", component: NoMatch}]
    ]
], document.body);

foo.js

render([
    [Route, {path: "/", component: App},
      [Route, {path: "about", component: About}],
      [Route, {path: "users", component: Users},
        [Route, {path: "/user/:userId", component: User}]
      ],
      [Route, {path: "*", component: NoMatch}]
    ]
], document.body);

foo.jsx

render((
  <Router>
    <Route path="/" component={App}>
      <Route path="about" component={About}/>
      <Route path="users" component={Users}>
        <Route path="/user/:userId" component={User}/>
      </Route>
      <Route path="*" component={NoMatch}/>
    </Route>
  </Router>
), document.body);