Combining message sending in PubSubJs

PubSubJs.js

/*
Copyright (c) 2010 Morgan Roderick http://roderick.dk

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*/
/*jslint evil: false, strict: false, undef: true, white: false, onevar:false, plusplus:false, indent:2 */
/*global setTimeout:true */
/** section: PubSub
* PubSubJS is a dependency free library for doing ['publish/subscribe'](http://en.wikipedia.org/wiki/Publish/subscribe)
* messaging in JavaScript.
*
* In order to not have surprising behaviour where the execution chain generates more than one message,
* publication of messages with PubSub are done asyncronously (this also helps keep your code responsive, by
* dividing work into smaller chunkcs, allowing the event loop to do it's business).
*
* If you're feeling adventurous, you can also use syncronous message publication, which can lead to some very
* confusing conditions, when one message triggers publication of another message in the same execution chain.
* Don't say I didn't warn you.
*
* ##### Examples
*
* // create a function to receive the message
* var mySubscriber = function ( msg, data ) {
* console.log( msg, data );
* };
*
* // add the function to the list of subscribers to a particular message
* // we're keeping the returned token, in order to be able to unsubscribe from the message later on
* var token = PubSub.subscribe( 'MY MESSAGE', mySubscriber );
*
* // publish a message asyncronously
* PubSub.publish( 'MY MESSAGE', 'hello world!' );
*
* // publish a message syncronously, which is faster by orders of magnitude, but will get confusing
* // when one message triggers new messages in the same execution chain
* // USE WITH CATTION, HERE BE DRAGONS!!!
* PubSub.publishSync( 'MY MESSAGE', 'hello world!' );
*
* // unsubscribe from further messages, using setTimeout to allow for easy pasting of this code into an example :-)
* setTimeout(function () {
* PubSub.unsubscribe( token );
* }, 0)
**/
var PubSub = (function () {
  "use strict";
  
  var messages = {};
  var lastUid = -1;
  var undelivered;

  function deliverMessages() {
      var cur;
      while (cur = undelivered.shift()) {
        publishSync(cur.message, cur.data);
      }
      undelivered = null;
  }
  
  function publishSync(message, data) {
    if (!messages.hasOwnProperty(message))
        return false;

    var subscribers = messages[message];
    for (var i = 0, j = subscribers.length; i < j; i++) {
      try {
        subscribers[i].func(message, data);
      } catch(e) {
        throwExceptionLater(e);
      }
    }

    return true;
  }

  function throwExceptionLater(e) {
    setTimeout(function () { throw e; }, 0);
  }

  return {
    version: "1.0.1",

    /**
     * PubSub.publish( message[, data] ) -> Boolean
     * - message (String): The message to publish
     * - data: The data to pass to subscribers
     * - sync (Boolean): Forces publication to be syncronous, which is more confusing, but faster
     * Publishes the the message, passing the data to it's subscribers
     **/
    publish: function (message, data) {
      if (!messages.hasOwnProperty(message))
        return false;

      var cur = {message: message, data: data};
      if (undelivered) {
        // already doing event dispatch
        undelivered.push(cur);
      } else {
        undelivered = [cur];
        setTimeout(deliverMessages, 0);
      }

      return true;
    },
    
    /**
     * PubSub.publishSync( message[, data] ) -> Boolean
     * - message (String): The message to publish
     * - data: The data to pass to subscribers
     * - sync (Boolean): Forces publication to be syncronous, which is more confusing, but faster
     * Publishes the the message synchronously, passing the data to it's subscribers
     **/
    publishSync: publishSync,

    /**
     * PubSub.subscribe( message, func ) -> String
     * - message (String): The message to subscribe to
     * - func (Function): The function to call when a new message is published
     * Subscribes the passed function to the passed message. Every returned token is unique and should be stored if you need to unsubscribe
     **/
   subscribe: function (message, func) {
     // message is not registered yet
     if (!messages.hasOwnProperty(message)) {
       messages[message] = [];
     }
     
     // forcing token as String, to allow for future expansions without breaking usage
     // and allow for easy use as key names for the 'messages' object
     var token = (++lastUid).toString();
     messages[message].push({ token : token, func : func });
     
     // return token for unsubscribing
     return token;
    },

    /**
     * PubSub.unsubscribe( token ) -> String | Boolean
     * - token (String): The token of the function to unsubscribe
     * Unsubscribes a specific subscriber from a specific message using the unique token
     **/
    unsubscribe: function (token) {
      for (var m in messages) {
        if (messages.hasOwnProperty(m)) {
          for (var i = 0, j = messages[m].length; i < j; i++) {
            if (messages[m][i].token === token) {
              messages[m].splice(i, 1);
              return token;
            }
          }
        }
      }
      return false;
    }
  };
})();

unpublished jsperf: http://jsperf.com/pubsubjs-vs-jquery-custom-events/17

ticket to original author: mroderick/PubSubJS#3