main.js

import React from 'react';
import ReactDOM from 'react-dom';
import {Router, Route} from 'react-router';
import { createHistory } from 'history';
import config from './config';
import ga from 'react-ga';

import Landing from './pages/Landing';

ga.initialize(config.google.analyticsId);

let logPageView = () => { 
    ga.pageview(this.state.location.pathname); 
};

let routes = (
    <Router history={createHistory()} onUpdate={logPageView}>
        <Route path="/" component={Landing} />
    </Router>
)

ReactDOM.render(routes, document.querySelector('#app'));