Demonstrates YUI3 event subscription monitoring, for use with performance-intensive events.

performant-events.js

YUI().use("widget", function (Y) {
  var eventName = "frob",
    widg = new Y.Widget(),
    ce = widg.publish(eventName);
  ce.monitor("attach", function (handler) {
    var subs = ce.getSubs();
    console.log("handler attached!", subs);
    if (!ce.hasSubs()) {
        console.log("enabling performance-intensive event");
    }
  });
  ce.monitor("detach", function (handler) {
    console.log("handler detached!");
    if (!ce.hasSubs()) {
      console.log("disabling performance-intensive event");
    }
  });
  widg.on(eventName, function () {}).detach();
  widg.on(eventName, function (e) {
    console.log("fire: " + e.type);
  });
  widg.on(eventName, function () {}).detach();
  widg.fire(eventName);
}); 
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