Home.jsx

let Home = React.createClass({
  statics: {
    fetch(app) {
      return new Promise(function(resolve, reject) {
        setTimeout(resolve, 1000)
      })
    }
  },
  
  render() {
    return <p>Home</p>
  }
}

main.js

const app    = new App()
const target = document.querySelector("#app")

app.start(function() {

  Router.run(function(Handler, state) {
    let { query, params, routes } = state

    let requests = state.routes.filter(i => i.handler.fetch)
                        .map(i => i.handler.fetch(app, params, query))

    Promise.all(requests).then(function() {
      React.render(<Handler { ...state } app={ app } />, target)
    })
  })

})