function TracePubSub() {
  var events = {};

  this.publish = function (name, data) {
    var handlers = events[name];
    if (!!handlers === false) return;
    handlers.forEach(function (handler) {
      handler.call(this, data);
    });
  };

  this.subscribe = function (name, handler) {
    var handlers = events[name];
    if (!!handlers === false) {
      handlers = events[name] = [];
    }
    handlers.push(handler);
  };

  this.unsubscribe = function (name, handler) {
    var handlers = events[name];
    if (!!handlers === false) return;

    var handlerIdx = handlers.indexOf(handler);
    handlers.splice(handlerIdx);
  };
}

window.TracePubSub = new TracePubSub();