* JavaScript Pub Sub

Posted on April 28th, 2009 by Dave Johnson. Filed under JavaScript, Uncategorized.


I was talking to someone the other day about the observer pattern in JavaScript and I was reminded about this JavaScript method that is part of Complete UI.

nitobi.Event.prototype.subscribeOnce = function(method, context) {
  var guid = null;
  var _this = this;
  var func1 = function() {
    method.apply(context || null, arguments);
    _this.unSubscribe(guid);
  }
  guid = this.subscribe(func1);
  return guid;
}

subscribeOnce is a special sort of event subscription that rather than being being executed every time the event fires, the handler function is only executed once and then automatically unsubscribed from the event. It is obviously most useful for initialization stuff in JavaScript. There is some more info on JavaScript pub sub over on Ajaxian too.

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One Response to “JavaScript Pub Sub”

  1. null is not an object » Blog Archive » JavaScript Event Merging Says:

    [...] have a basic JavaScript object called the “Subject” that has subscribe, subscribeOnce (events that auto-unsubscribe themselves after being fired the first time), and notify methods on them. You can use the following merge function to have all subscribed code [...]

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