// Fires a custom event every time the hash changes. It does so by 
// checking for a change at a set interval (0.2 seconds by default).
// Also passes the current hash in the memo object to make things
// easier for event handlers.

(function() {
    
  var HashWatcher = {
      
    CURRENT: '',
    INTERVAL: 0.2,
    
    check: function(pe) {
      var hash = window.location.hash;
      if (HashWatcher.CURRENT != hash) {
        document.fire('hash:changed', { currentHash: hash });
        HashWatcher.CURRENT = hash;
      }
    }
  };
  
  new PeriodicalExecuter(HashWatcher.check, HashWatcher.INTERVAL);
  
})();