auth.js

var component = require('omniscient');
var react = require('react');
var immstruct = require('immstruct');

var appStructure = immstruct({
   currentUser: {
       username: void 0
   }
});

var Authentication = {
  // like a class instance, will be called by react-router
  statics: {
    willTransitionTo: function (transition) {
      // You can access the global state here. That isn't really 
      // connected to a specific component
      if (appStructure.cursor('currentUser').deref() === void 0) {
        Login.attemptedTransition = transition;
        transition.redirect('/login');
      }
    }
  }
};

var SecureComponent = component(Authentication, function () {
    return React.DOM.h1({}, 'This is super secret');
});

appStructure.on('swap', render);
render();

// Just with react-router, instead of rendering directly
function render () {
  React.render(Welcome(structure.cursor()), document.body);
}

/* something like: (incomplete syntax)
var routes = (
  <Route handler={App}>
    <Route name="secure" handler={SecureComponent.jsx}/>
  </Route>
);
Route.render(routes, ...)
*/