Publish Subscribe JS Util Lib

pubsub_V2.js

/* Simple PubSub
==================================================================================================== */

(function(d) {

	// the topic/subscription hash
	var cache = d.c_ || {};

	d.publish = function(topic, args) {
		// summary:
		//      Publish some data on a named topic.
		// topic: String
		//      The channel to publish on
		// args: Array?
		//      The data to publish. Each array item is converted into an ordered
		//      arguments on the subscribed functions.
		//
		// example:
		//      Publish stuff on '/some/topic'. Anything subscribed will be called
		//      with a function signature like: function(a,b,c){ ... }
		//
		//      publish("/some/topic", ["a","b","c"]);

		var subs = cache[topic];
		var len = subs ? subs.length : 0;

		//can change loop or reverse array if the order matters
		while (len--) {
			subs[len].apply(d, args || []);
		}
	};

	d.subscribe = function(topic, callback) {

		// summary:
		//      Register a callback on a named topic.
		// topic: String
		//      The channel to subscribe to
		// callback: Function
		//      The handler event. Anytime something is publish'ed on a
		//      subscribed channel, the callback will be called with the
		//      published array as ordered arguments.
		//
		// returns: Array
		//      A handle which can be used to unsubscribe this particular subscription.
		//
		// example:
		//      subscribe("/some/topic", function(a, b, c){ /* handle data */ });

		if (!cache[topic]) {
			cache[topic] = [];
		}

		cache[topic].push(callback);
		return [topic, callback];
	};

	d.unsubscribe = function(handle) {
		// summary:
		//      Disconnect a subscribed function for a topic.
		// handle: Array
		//      The return value from a subscribe call.
		// example:
		//      var handle = subscribe("/some/topic", function(){});
		//      unsubscribe(handle);

		var subs = cache[handle[0]];
		var callback = handle[1];
		var len = subs ? subs.length : 0;

		while (len--) {
			if (subs[len] === callback) {
				subs.splice(len, 1);
			}
		}
	};

})(this);