PubSubJS vs. jQuery custom events

JavaScript performance comparison

Revision 68 of this test case created

Info

An attempt at showing that PubSubJS is faster than using jQuery custom evens for publish/subscribe style messaging.

It's certainly not as rich in features, and I am happy with that.

Introducing PubSubJS

Preparation code

<script src="//ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js"></script>
<script>
;(function(root, factory){
'use strict';

// CommonJS
if (typeof exports === 'object'){
module.exports = factory();

// AMD
} else if (typeof define === 'function' && define.amd){
define(factory);
// Browser
} else {
root.PubSub = factory();
}
}( ( typeof window === 'object' && window ) || this, function(){

'use strict';

var PubSub = {
name: 'PubSubJS',
version: '1.3.3'
},
messages = {},
lastUid = -1;

/**
* Returns a function that throws the passed exception, for use as argument for setTimeout
* @param { Object } ex An Error object
*/
function throwException( ex ){
return function reThrowException(){
throw ex;
};
}

function callSubscriberWithDelayedExceptions( subscriber, message, data ){
try {
subscriber( message, data );
} catch( ex ){
setTimeout( throwException( ex ), 0);
}
}

function callSubscriberWithImmediateExceptions( subscriber, message, data ){
subscriber( message, data );
}

function deliverMessage( originalMessage, matchedMessage, data, immediateExceptions ){
var subscribers = messages[matchedMessage],
callSubscriber = immediateExceptions ? callSubscriberWithImmediateExceptions : callSubscriberWithDelayedExceptions,
i, j;

if ( !messages.hasOwnProperty( matchedMessage ) ) {
return;
}

for ( i = 0, j = subscribers.length; i < j; i++ ){
callSubscriber( subscribers[i].func, originalMessage, data );
}
}

function createDeliveryFunction( message, data, immediateExceptions ){
return function deliverNamespaced(){
var topic = String( message ),
position = topic.lastIndexOf( '.' );

// deliver the message as it is now
deliverMessage(message, message, data, immediateExceptions);

// trim the hierarchy and deliver message to each level
while( position !== -1 ){
topic = topic.substr( 0, position );
position = topic.lastIndexOf('.');
deliverMessage( message, topic, data );
}
};
}

function messageHasSubscribers( message ){
var topic = String( message ),
found = messages.hasOwnProperty( topic ),
position = topic.lastIndexOf( '.' );

while ( !found && position !== -1 ){
topic = topic.substr( 0, position );
position = topic.lastIndexOf('.');
found = messages.hasOwnProperty( topic );
}

return found;
}

function publish( message, data, sync, immediateExceptions ){
var deliver = createDeliveryFunction( message, data, immediateExceptions ),
hasSubscribers = messageHasSubscribers( message );

if ( !hasSubscribers ){
return false;
}

if ( sync === true ){
deliver();
} else {
setTimeout( deliver, 0 );
}
return true;
}

/**
* PubSub.publish( message[, data] ) -> Boolean
* - message (String): The message to publish
* - data: The data to pass to subscribers
* Publishes the the message, passing the data to it's subscribers
**/
PubSub.publish = function( message, data ){
return publish( message, data, false, PubSub.immediateExceptions );
};

/**
* PubSub.publishSync( message[, data] ) -> Boolean
* - message (String): The message to publish
* - data: The data to pass to subscribers
* Publishes the the message synchronously, passing the data to it's subscribers
**/
PubSub.publishSync = function( message, data ){
return publish( message, data, true, PubSub.immediateExceptions );
};

/**
* 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
**/
PubSub.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 = String(++lastUid);
messages[message].push( { token : token, func : func } );

// return token for unsubscribing
return token;
};

/**
* PubSub.unsubscribe( tokenOrFunction ) -> String | Boolean
* - tokenOrFunction (String|Function): The token of the function to unsubscribe or func passed in on subscribe
* Unsubscribes a specific subscriber from a specific message using the unique token
* or if using Function as argument, it will remove all subscriptions with that function
**/
PubSub.unsubscribe = function( tokenOrFunction ){
var isToken = typeof tokenOrFunction === 'string',
key = isToken ? 'token' : 'func',
succesfulReturnValue = isToken ? tokenOrFunction : true,

result = false,
m, i;

for ( m in messages ){
if ( messages.hasOwnProperty( m ) ){
for ( i = messages[m].length-1 ; i >= 0; i-- ){
if ( messages[m][i][key] === tokenOrFunction ){
messages[m].splice( i, 1 );
result = succesfulReturnValue;

// tokens are unique, so we can just return here
if ( isToken ){
return result;
}
}
}
}
}

return result;
};

return PubSub;
}));
</script>
<script>
  var callback1 = function() {};
  var callback2 = function() {};
  var payload = {
   somekey: 'some value'
  };
  var body;
  
  // let's use jQuery.ready to make sure that the DOM is ready,
  // before trying to work with it
  jQuery(function() {
   // we'll use the body element to exchange messages for jQuery
   // if using deeper nested elements, jQuery will be slower, as custom events bubble
   body = $('body');
  
   // subscribe our callback1 function to the custom event for jQuery, only once
   body.bind('my-event', callback1);
  
   // subscribe our callback2 function to the message for PubSub
   PubSub.subscribe('my-event', callback2)
  });
</script>

Preparation code output

Test runner

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Testing in unknown unknown
Test Ops/sec
jQuery - trigger
 
body.trigger('my-event', payload);
 pending…
PubSub - publish - asyncronous
 
PubSub.publish('my-event', payload);
 pending…
PubSub - publish - syncronous
 
PubSub.publish('my-event', payload, true);
 pending…

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