javascript pub/sub event helper

gistfile1.txt

var events = (function() {
  var topics = {};

  return {
    sub: function(topic, listener) {
      topics[topic] = topics[topic] || [];

      var index = topics[topic].push(listener) - 1;

      // Provide handle back for removal of topic
      return {
        remove: function() {
          topics[topic].splice(index, 1);
          if (topics[topic].length === 0) delete topics[topic];
        }
      };
    },
    pub: function(topic, info) {
      if (!topics.hasOwnProperty(topic)) return;

      topics[topic].forEach(function(item) {
        item(info || {});
      });
    }
  };
})();

//angular has $boardcast and $on

//if running on browser, there is also webapi
//fire event
document.dispatchEvent(new CustomEvent('assetInstance/' + key, {detail: val}));

//subscribe event
var subAssetChange = function(event){
  updateUI();
};
document.addEventListener('assetInstance/' + $scope.asset.flake_id, subAssetChange);

$scope.$on("$destroy", function() {
  if (subAssetChange) {
    document.removeEventListener('assetInstance/' + $scope.asset.flake_id, subAssetChange);
  }
});