example.js

FlowRouter.route('/home', {
  // calls just before the action
  triggersEnter: [setSite],
  action: function() {
    // do something you like
  });
  
  setSite = function(){
    var url = window.location.hostname;
    var urlBits = url.split('.');
    //example hostnamedocs.meteor.com
    // urlBits[0] || subdomain
    // urlBits[1] || domain
    // urlBits[2] || domain extention
    // set some session vals from this
    
  }