jQuery Tiny Pub/Sub: A really, really, REALLY tiny pub/sub implementation for jQuery.

HEY-YOU.md

This is now an actual repo:

https://github.com/cowboy/jquery-tiny-pubsub

jquery.ba-tinypubsub.js

/* jQuery Tiny Pub/Sub - v0.7 - 10/27/2011
 * http://benalman.com/
 * Copyright (c) 2011 "Cowboy" Ben Alman; Licensed MIT, GPL */

(function($) {

  var o = $({});

  $.subscribe = function() {
    o.on.apply(o, arguments);
  };

  $.unsubscribe = function() {
    o.off.apply(o, arguments);
  };

  $.publish = function() {
    o.trigger.apply(o, arguments);
  };

}(jQuery));

jquery.ba-tinypubsub.min.js

/* jQuery Tiny Pub/Sub - v0.7 - 10/27/2011
 * http://benalman.com/
 * Copyright (c) 2011 "Cowboy" Ben Alman; Licensed MIT, GPL */
(function(a){var b=a({});a.subscribe=function(){b.on.apply(b,arguments)},a.unsubscribe=function(){b.off.apply(b,arguments)},a.publish=function(){b.trigger.apply(b,arguments)}})(jQuery)

I wrapped this into AMD module to use it with require.js

define(function () {

    "use strict";

    /**
     *    Events. Pub/Sub system for Loosely Coupled logic.
     *    Based on Peter Higgins' port from Dojo to jQuery
     *    https://github.com/phiggins42/bloody-jquery-plugins/blob/master/pubsub.js
     *
     *    Re-adapted to vanilla Javascript
     *
     *    ----------------------------------------------------------
     *    And then wrapped to AMD Module by Dragan Bajcic @kodisha
     *
     *    @class Events
     */
    return {
        cache : {},
        /**
         *    Events.publish
         *    e.g.: Events.publish("/Article/added", [article], this);
         *
         *    @class Events
         *    @method publish
         *    @param topic {String}
         *    @param args    {Array}
         *    @param scope {Object=} Optional
         */
        publish : function (topic, args, /** {Object=} */ scope) {

            console.log('publish',topic, args);
            if (this.cache[topic]) {
                var thisTopic = this.cache[topic],
                    i = thisTopic.length - 1;

                for (i ; i >= 0 ; i -= 1) {
                    thisTopic[i].apply(scope || this, args || []);
                }
            }
        },
        /**
         *    Events.subscribe
         *    e.g.: Events.subscribe("/Article/added", Articles.validate)
         *
         *    @class Events
         *    @method subscribe
         *    @param topic {String}
         *    @param callback {Function}
         *    @return Event handler {Array}
         */
        subscribe : function (topic, callback) {

            console.log('subscribe', topic, callback);
            if (!this.cache[topic]) {
                this.cache[topic] = [];
            }
            this.cache[topic].push(callback);
            return [topic, callback];
        },
        /**
         *    Events.unsubscribe
         *    e.g.: var handle = Events.subscribe("/Article/added", Articles.validate);
         *        Events.unsubscribe(handle);
         *
         *    @class Events
         *    @method unsubscribe
         *    @param handle {Array}
         *    @param completly {Boolean}
         *    @return {type description }
         */
        unsubscribe : function (handle, completly) {
            var t = handle[0],
                i = this.cache[t].length - 1;

            if (this.cache[t]) {
                for (i ; i >= 0 ; i -= 1) {
                    if (this.cache[t][i] === handle[1]) {
                        this.cache[t].splice(this.cache[t][i], 1);
                        if (completly) {
                            delete this.cache[t];
                        }
                    }
                }
            }
        }
    };

});

I have only one concern/suggestion to this relatively simple PubSub - it doesn't take into account published events that have already happened (in the past). Why is this important? Assume for a second that I want to subscribe to an event that had already happened, or I dont know that it happened, but still want my new subscriber to be triggered with the last-published values? My suggestion is to add something like this:

(function($) {

var o = $({}), pastEvents = {};

$.subscribe = function() {
var type = arguments.slice(0, 1)[0],
handler = arguments.slice(-1)[0];
//Fire your subscribe handler if event has already happened
if(type in pastEvents) {
pastEvents[type].done(function() {
handler.apply(o, arguments);
});
}
//Subscribe to future events as well
o.on.apply(o, arguments);
};

$.unsubscribe = function() {
o.off.apply(o, arguments);
};

$.publish = function() {
var type = arguments.slice(0, 1)[0],
data = arguments.slice(1)[0];
//Preserve data for future subscribers to this event
pastEvents[type] = $.Deferred().resolve(data).promise();
o.trigger.apply(o, arguments);
};

}(jQuery));

Even smaller just for sillyness

var o=$({}),s='subscribe';
$.each({on:s,off:'un'+s,trigger:'publish'},function(k,v){$[v]=function(){o[k].apply(o,arguments)};});

If we're talking about relative sizes, why use "publish/subscribe" nomenclature? Just stick with "on/off/trigger" (or my preferred "on/off/do").

UPDATE I just found out why the "pros" stick to trigger instead of do (boo <IE9).

Example: https://gist.github.com/zaus/4756518

/* jQuery Tinier Pub/Sub - v0.9b - "on/off/do version" - 2013-02-11
 * original by http://benalman.com/ 10/27/2011
 * Original Copyright (c) 2011 "Cowboy" Ben Alman; Licensed MIT, GPL */

(function($) {

  // "topic" holder
  var o = $({});

  // attach each alias method
  $.each({on:0,off:0,"go":'trigger'}, function(alias,method) {
    $[alias] = function(topic, callbackOrArgs) {
        o[method || alias].apply(o, arguments);
    }
  });

}(jQuery));

@connected - what's the default event you're trying to prevent? isn't this limited to the arbitrary hidden topic var o? just curious.

@kodi thanks for the requirejs module implementation!

How would you add support for wildcards in the topic name? Does it even make sense as jQuery doesn't support wildcards for event names? Or is using a standalone pub/sub library the better approach?

I know some javascript and little of jQuery (been playing with Ember, just for fun). I understand the on off methods, but I do not understand what var o = $({}); does. Can anyone please explain?

As always, google doesn't consider these braces and the $ in its search results.

@gmanish var o = $({}) simply creates a jQuery collection with an empty object {} that becomes the recipient of all the event triggers. As other comments show, the recipient could be anything like $('<b />').

I am telling you this is working really good.

Made a Typescript version of this here: https://gist.github.com/ahmed-musallam/d12a71b8a3ec8cebf52c12f81f3da154

@cowboy this gist is getting spammed

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