My first bit of React code worth sharing.

01_mixins_Secure.js

var React = require('react');
var Router = require('react-router');
var SessionStore = require('../stores/SessionStore');
var Stash = require('../utils/Stash');

function authentication(transition) {
  if (!SessionStore.isLoggedIn()) {
    Stash.set('onLogin', transition.retry);
    transition.redirect('login');
    return false;
  }

  return true;
}

function Secure(authorization) {
  return {

    mixins: [Router.Navigation],

    propTypes: {
      isLoggedIn: React.PropTypes.bool.isRequired
    },

    statics: {
      willTransitionTo: function(transition, params, query, callback) {
        if (!authentication(transition)) {
          callback();
        } else if (authorization) {
          authorization(transition, params, query, callback);
          if (authorization.length < 4) callback();
        } else {
          callback();
        }
      }
    },

    componentDidUpdate: function(prevProps, prevState) {
      this.props.isLoggedIn || this.transitionTo('login');
    }

  };
}

module.exports = Secure;

02_components_LoginPage.js

var React = require('react');
var Router = require('react-router');
var Stash = require('../utils/Stash');

var LoginPage = React.createClass({

  mixins: [Router.Navigation],

  // ...

  componentDidUpdate: function(prevProps, prevState) {
    if (this.props.isLoggedIn && !prevProps.isLoggedIn) {
      var onLogin = Stash.get('onLogin');
      onLogin ? onLogin : this.transitionTo('home');
    }
  }

  // ...

});

module.exports = LoginPage;

03_components_SecurePage.js

var React = require('react');
var Secure = require('../mixins/Secure');

var SecurePage = React.createClass({
  
  mixins: [Secure()]
  
  // ...
  
});

module.exports = SecurePage;

04_components_AuthorizationPage.js

var React = require('react');
var Secure = require('../mixins/Secure');

function authorization(transition) {
  // authorization logic...
}

var AuthorizationPage = React.createClass({
  
  mixins: [Secure(authorization)]
  
  // ...
  
});

module.exports = AuthorizationPage;