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What is scaleApp?

scaleApp is a tiny JavaScript framework for scalable and maintainable One-Page-Applications / Single-Page-Applications. The framework allows you to easily create complex web applications.

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You can dynamically start and stop/destroy modules that acts as small parts of your whole application.

Architecture overview

scaleApp is based on a decoupled, event-driven architecture that is inspired by the talk of Nicholas C. Zakas - "Scalable JavaScript Application Architecture" (Slides). There also is a little Article that describes the basic ideas.

scaleApp architecture


A module is a completely independent part of your application. It has absolutely no reference to another piece of the app. The only thing the module knows is your sandbox. The sandbox is used to communicate with other parts of the application.


The main purpose of the sandbox is to use the facade pattern. In that way you can hide the features provided by the core and only show a well defined custom static long term API to your modules. This is actually one of the most important concept for creating mainainable apps. Change plugins, implementations etc. but keep your API stable for your modules. For each module a separate sandbox will be created.


The core is responsible for starting and stopping your modules. It also handles the messages by using the Publish/Subscribe (Mediator) pattern


Plugins can extend the core or the sandbox with additional features. For example you could extend the core with basic functionalities (like DOM manipulation) or just aliases the features of a base library (e.g. jQuery).


  • loose coupling of modules
  • small (about 300 sloc / 8,7k min / 3.3k gz)
  • no dependencies
  • modules can be tested separately
  • replacing any module without affecting other modules
  • extendable with plugins
  • browser and Node.js support
  • flow control
  • AMD & CommonJS support
  • framework-agnostic


scaleApp itself is very small but it can be extended with plugins. There already are some plugins available:

  • mvc - simple MVC
  • i18n - multi language UIs
  • permission - take care of method access
  • state - Finite State Machine
  • submodule - cascade modules
  • dom - DOM manipulation
  • strophe - XMPP communication
  • modulestate - event emitter for init and destroy
  • util - helper methods like mixin, uniqueId etc.
  • ls - list modules, instances & plugins

You can easily define your own plugin (see plugin section).


Latest stable 0.4.x version

or use the CDN:

<script src="//" ></script>

Old stable 0.3.x version


There are some API changes in version 0.4.x (see Changelog). Docs for v0.3.9 can be found within the tar/zip file.

Unstable version

git clone git://

Quick Start

Link scaleApp.min.js in your HTML file:

<script src="scaleApp.min.js"></script>

or use the CDN:

<script src="//" ></script>

If you're going to use it with node:

npm install scaleapp --save
var sa = require("scaleapp");

or use bower:

bower install scaleapp

Create your own Sandbox

First of all create your own sandbox. By doing that you're able to guarantee a stable maintainable API for your modules.

var MySandbox = function(core, instanceId, options, moduleId) {

  // define your API
  this.myFooProperty = "bar";

  // e.g. provide the Mediator methods 'on', 'emit', etc.

  // ... or define your custom communication methods
  this.myEmit = function(channel, data){
    core.emit(channel + '/' + instanceId, data);

  // maybe you'd like to expose the instance ID = instanceId;

  return this;

// ... and of course you can define shared methods etc. = function() { /*...*/ };

Create a core

Now create a new core instance with your sandbox:

var core = new scaleApp.Core(MySandbox);

Register modules

core.register( "myModuleId", function( sandbox ){
  return {
    init:    function(){ /*...*/ },
    destroy: function(){ /*...*/ }

As you can see the module is a function that takes the sandbox as a parameter and returns an object that has two functions init and destroy (the latter is optional). Of course your module can be any usual class with those two functions.

var MyGreatModule = function(sandbox){
  return {
    init:    function(){ alert("Hello world!"); }
    destroy: function(){ alert("Bye bye!");     }

core.register("myGreatModule", MyGreatModule);

The init function is called by the framework when the module is supposed to start. The destroy function is called when the module has to shut down.

Asynchronous initialization

You can also init or destroy you module in a asynchronous way:

var MyAsyncModule = function(sandbox){
  return {
    init: function(options, done){
        // ...
    destroy: function(done){

core.register("myGreatModule", MyGreatModule);
core.start("myGreatModule", { done:function(){
  alert("now the initialization is done");

Start modules

After your modules are registered, start your modules:

  .start( "myModuleId" )
  .start( "anOtherModule", function(err){
    // 'anOtherModule' is running now

Start options

You may also want to start several instances of a module:

core.start( "myModuleId", {instanceId: "myInstanceId" } );
core.start( "myModuleId", {instanceId: "anOtherInstanceId" });

All you attach to options is accessible within your module:

core.register( "mod", function(sandbox){
  return {
    init: function(opt){
      (opt.myProperty === "myValue")  // true
    destroy: function(){ /*...*/ }

core.start("mod", {
  instanceId: "test",
  options: { myProperty: "myValue" }

If all your modules just needs to be instanciated once, you can simply starting them all:


To start some special modules at once you can pass an array with the module names:


You can also pass a callback function:

  // do something when all modules were initialized

Moreover you can use a separate sandbox for each instance:

var MySandbox = function(){/*...*/};
core.start("module", { sandbox: MySandbox });


It's obvious:

core.stop(); // stops all running instances


If the module needs to communicate with others, you can use the emit and on methods.


The emit function takes three parameters whereas the last one is optional:

  • topic : the channel name you want to emit to
  • data : the data itself
  • cb : callback method

The emit function is accessible through the sandbox (as long as you exposed the Mediator methods of course):

sandbox.emit( "myEventTopic", myData );


A message handler could look like this:

var messageHandler = function( data, topic ){
  switch( topic ){
    case "somethingHappend":
      sandbox.emit( "myEventTopic", processData(data) );
    case "aNiceTopic":
      justProcess( data );

... and it can listen to one or more channels:

sub1 = sandbox.on( "somthingHappend", messageHandler );
sub2 = sandbox.on( "aNiceTopic", messageHandler );

Or just do it at once:

  topicA: cbA,
  topicB: cbB,
  topicC: cbC

You can also subscribe to several channels at once:

sandbox.on(["a", "b"], cb);

If you prefer a shorter method name you can use the alias on.

attache and detache

A subscription can be detached and attached again:

sub.detach(); // don't listen any more
sub.attach(); // receive upcoming messages


You can unsubscribe a function from a channel"a-channel", callback);

And you can remove a callback function from all channels;

Or remove all subscriptions from a channel:"channelName");

Flow control


var task1 = function(next){
    next(null, "one");

var task2 = function(next){
  next(null, "two");

scaleApp.util.runSeries([task1, task2], function(err, result){
  // result is ["one", "two"]

// console output is:
// "task1"
// "task2"


var task1 = function(next){
    next(null, "a");

var task2 = function(next){
  next(null, "b");

scaleApp.util.runParallel([task1, task2],function(err,result){
  // result is ["a", "b"]

// console output is:
// "task2"
// "task1"

There is also a little helper tool to run the same async task again and again in parallel for different values:

var vals = ["a","b", "c"];
var worker = function(val, next){
    next(err, result);

scaleApp.util.doForAll(args, worker, function(err, res){
  // fini


var task1 = function(next){
    next(null, "one", "two");

var task2 = function(res1, res2, next){
  // res1 is "one"
  // res2 is "two"
  next(null, "yeah!");

scaleApp.util.runWaterfall([task1, task2], function(err, result){
  // result is "yeah!"


There are some plugins available within the plugins folder. For more information look at the plugin README.

Register plugins

A single plugin can be registered with it option object in that way:


If you want to register multiple plugins at once:

  { plugin: plugin3, options: options3 }

Write your own plugin

It's easy:

  core.helloWorld = function(){ alert("helloWorld"); };

Here a more complex example:

core.use(function(core, options, done){

  // extend the core
  core.myCoreFunction = function(){ alert("Hello core plugin") };
  core.myBoringProperty = "boring";

  // extend the sandbox class
  core.Sandbox.prototype.myMethod = function(){/*...*/};

  // define a method that gets called when a module starts
  var onModuleInit = function(instanceSandbox, options, done){

    // e.g. define sandbox methods dynamically
    if (options.mySwitch){
      instanceSandbox.appendFoo = function(){

    // or load a something asynchronously

      // do something...
      // now tell scaleApp that you're done

  // define a method that gets called when a module stops
  var onModuleDestroy = function(done){

  // don't forget to return your methods
  return {
    init: onModuleInit,
    destroy: onModuleDestroy



core.myCoreFunction() // alerts "Hello core plugin"

var MyModule = function(sandbox){
  init: function(){ sandbox.appendFoo(); },  // appends "foo" to the container

Build browser bundles

If you want scaleApp bundled with special plugins type

grunt custom[:PLUGIN_NAME]

e.g. grunt custom:dom:mvc creates the file scaleApp.custom.js that contains scaleApp itself the dom plugin and the mvc plugin.



  • scaleApp.VERSION - the current version of scaleApp
  • scaleApp.Mediator - the Mediator class
  • scaleApp.Sandbox - the Sandbox class
  • scaleApp.Core - the Core class


// use default sandbox
var core = new scaleApp.Core();

// use your own sandbox
var core = new scaleApp.Core(yourSandboxClass);
  • core.register(moduleName, module, options) - register a module
  • core.use(plugin, options) - register a plugin
  • core.use(pluginArray) - registers an array of plugins
  • core.boot(callback) - initialize plugins (will be executed automatically on ´start´)
  • core.start(moduleId, options, callback) - start a module
  • core.stop(instanceId, callback) - stop a module


// create a mediator
var mediator = new scaleApp.Mediator();

// create a mediator with a custom context object
var mediator = new scaleApp.Mediator(context);

// create a mediator with cascaded channels
var mediator = new scaleApp.Mediator(null, true);
  • mediator.emit(channel, data, callback)
  • mediator.on(channel, callback, context)
  •, callback)
  • mediator.installTo(context, force)
  • mediator.send(channel, payload, callback)
  • mediator.pipe(source, target, mediator)
// subscribe
var subscription = mediator.on(channel, callback, context);
  • subscription.detach - stop listening
  • subscription.attach - resume listening
var fn  = function(){ /*...*/ };
var obj = { emit: fn };

// the installTo method prevents existing properties by default
obj.emit === fn // true

// set the second paramater to 'true'
// to force the mediator to override existing propeties
mediator.installTo(obj, true);
obj.emit === mediator.emit // true


This is the default sandbox of scaleApp. It's a better idea to use your own one.

var sandbox =  new scaleApp.Sandbox(core, instanceId, options, moduleId)` - create a Sandbox
  • sandbox.emit is mediator.emit
  • sandbox.on is mediator.on
  • is




npm test


Within the examples directory you can find some basic examples that might help you.


scaleApp is licensed under the MIT license. For more information have a look at LICENCE.txt.


scaleApp is a JavaScript framework for scalable and maintainable One-Page-Applications








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