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Browser/nodejs reactive programming and data driven DOM manipulation with modular components.

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Quick start


npm install milojs


bower install milo


npm install
npm install -g grunt-cli
grunt test

To run all tests, including browser tests:

grunt tests



    <title>Binding example</title>
    <script src="milo.bundle.js"></script>
    <script src="index.js"></script>
    <input type="text" ml-bind="[Data]:myField">
    <div ml-bind="[Data]:myCurrentValue"></div>
    <button ml-bind="[Events]:myTestButton">
    	<span ml-bind=":myTestValue"></span>
      <h2>I am connected:</h2>
      <span ml-bind="[Data]:myTestValue2"></span>


// run when DOM is ready
milo(function () {
    // create and bind components with milo.binder
    var scope = milo.binder();

    // attach subscriber to data change event via data facet
    // of myField component'', function(msg, data) {;
      // alternatively:
      // scope.myCurrentValue.el.innerHTML = data.newValue;

    // attach subscriber to click event via events facet
    // of myTestButton component'click', function(msg, event) {
    	scope.myTestValue.el.innerHTML =;

    // connect two components directly via their data facets
    // using milo.minder
    milo.minder(, '->',;

Note on runtime parameter type checking

Milo uses check module (milo.util.check - forked from check package of Meteor framework) for runtime checking of parameter types. It is highly recommended to switch off this checks in production using: milo.config({ check: false }).

Depending on your application, it can improve performance more than twice.


Getting started

Introduction to binding

Introduction to data facet

Introduction to messengers

Introduction to models

Introduction to minder

Introduction to lists

Article about creating milo Rolling Your Own Framework on tuts+


The more advanced sample is Todos app in todomvc folder.


npm link

rm -R -f -d node_modules/milojs
npm link milojs # link milo to your current project to use with browserify

grunt # rebuild milo bundle every time you change any .js file

Additionally you can setup grunt in your project to rebuild it whenever milo bundle changes.

Please make sure you run grunt tests before committing (not just grunt test that is run by TravisCI automatically) - it will run all tests, including browser tests.


Modular design

Although milo is packaged as one bundle, it has very modular structure. It consists of several independent modules that can be used together or separately and that are designed to simplify common application tasks rather than to create any particular application structure.

Some modules in milo can be used only in browser (Component, ComponentFacet, milo.binder), some both in browser and in nodejs (Messenger and its related classes, Model, Connector, milo.minder).

Milo itself uses browserify to package bundle, but any modules system can be used in an app that uses milo - milo does not suggest any application structure.


Component is designed to simplify the management of DOM. Component is attached to a certain DOM element. Attaching several components to the same DOM element is usually an application (or milo) design mistake, so if it happens an error will be logged to console.

Components allow very easy creation of subclasses that are defined as a collection of configured "facets". For example, see the definition of MLSelect UI component.

There is a Component template to simplify creation of your own components.

See Component documentation.

Component facet

ComponentFacet is a base class, subclasses of which group methods related to behaviours of components.

You would rarely need to instantiate a facet - when a component is created it creates all its facets

There are the following facets defined in milo:

  • Container - a special facet that creates a scope of components
  • Dom - a collection of helper methods simplifying DOM manipulation of component element
  • Events - gives a convenient API to subscribe to DOM events
  • Data - an api to manipulate DOM tree inside component element as data, allowing both getting/setting structured data from/to many DOM elements at once and creating reactive data connection of Models (see below) to DOM.
  • List and Item - allow creating lists in DOM from arays in your data. Component class using any of these facets require Data facet (will be added automatically) that should be used to get/set list data and to create reactive data connection.
  • Template - simplifies rendering of component DOM element from template.
  • Css - Allows you to bind DOM data, or models to css classes using declaritive rules in the facet config.
  • Frame - manages sending/receiveing messages to/from iframe.
  • Drag - allows easy management of draggable DOM elements.
  • Drop - helps creating drop targets.
  • Model - simple wrapper for milo Model (see below), helping to store data on component.

There is a Component facet template to simplify creation of your own facets. All facets of components should be subclasses of ComponentFacet.

DOM binding and creation of component instances

Instances of your components are usually created automatically when you call milo.binder based on information about components classes, facets and component name in ml-bind attribute (can be changed via milo.config).

To make your components available to milo their classes should be registered in components registry (milo.registry.components). If you define new facets, their classes should also be registered (in milo.registry.facets).

As registering of components and facets classes usually happens in the same module (file) that defines the class, you have to execute this module. If you use broserify for module management it is enough to use:


in any other module that is executed or required.


milo supplies internal messaging classes that can also be used for application needs. All facets in milo have an instance of Messenger attached to them that defines messaging api specific to the facet, in most cases connecting to some external source (usually DOM events).

Messenger instances use instances of MessageSource subclasses to connect to external sources and instances of MessengerAPI subclasses to create higher level internal messages and transform message data. This architecture allows creating an advanced functionality in just a few lines of code.

See Messenger documentation.


milo defines Model to allow safe access to the data without the need to worry whether the data was set (it never throws when you access data when you get properties of undefined objects) and to enable possibility to subscribe to data changes similar to what experimental Object.observe and Array.observe APIs allow.

Using Model does not require these APIs, and unlike these APIs it allows subscribing to changes on properties of your Models to any depth.

See Model demo and Model documentation.


milo defines this class to manage reactive connection between objects that implement data messaging API. Both instances of Data facet and of Model are such objects.

You can create one- or two-way connections, define the depth of your data structures you want to observe, turn these connections off, e.g. when you want to make many Model changes without causing DOM updates.

These connections do not have overhead of comparing data in the loop like angularjs does and do not cause any performance degradation when many connected objects exist.

Very soon Connector instances will support structure translation allowing creating reactive connections between models with fixed structures and DOM trees with flexible structures.

One or multiple reactive connections can be created with milo.minder.

See Connector documentation.

Views and application management

  • milo.loader - loading subviews into page.
  • milo.mail - applicaiton level messenger that also defines domready event and simplifies routing of messages between iframes (see Frame facet).
  • milo.config - configuring milo settings.


  • check - check parameter types (forked from check package of Meteor framework).
  • logger - configurable logger with log levels.
  • request - HTTP requests library.
  • dom - library to manipulate DOM elements.

Why Milo?

Milo name was chosen because of Milo Minderbinder, a war profiteer from Catch 22. Having started from managing mess operations, he expanded them into a profitable trading enterprise, that connected everybody with everything, and in that Milo and everybody else "has a share".

Milo the framework has the module binder, that binds DOM elements to components (via special ml-bind attribute), and the module minder that allows establishing live reactive connections between different data sources (Model and Data facet of components are such data sources).

Coincidentally, Milo can be read as an acronym of MaIL Online.

Aren't there enough browser frameworks?

All frameworks we could lay our hands on were either too primitive leaving us to write too much code of our own (jQuery, Backbone) or too limiting, with enough magic to build simple application really fast but with limited control over precise functioning of the framework (Angular, Ext).

What we always wanted was a framework that would allow

  • developing applications in a declarative way with reactive bindings of models to views
  • creating reactive data bindings between different models in application to manage data propagation in a declarative rather than in imperative style
  • inserting validators and translators in these bindings, so we can bind views to data models rather than to view models like in AngularJS.
  • precise control over components linked to DOM elements.
  • flexibility of views management allowing both to automatically manipulate DOM on model changes and to re-render some sections using any __ templating engine__ in cases where rendering is more efficient than DOM manipulation
  • ability to dynamically create UI
  • being able to hook into mechanisms behind data reactivity and to precisely control view updates and data flow
  • being able to extend functionality of components supplied by framework and to create new components.

We could not find such framework so we started developing Milo in parallel with the application that uses it.


###Prototype based inheritance

milo relies on JavaScript prototypes to build framework blocks.

JavaScript is a very dynamic language. It allows writing functions that create classes (Component.createComponentClass) which allowed to implement a composition pattern where each component class is created as collection of pre-defined blocks (facets) with configuration of a facet that is specific to a constructed class (it has some similarity to Ext components, although they are not created from blocks).

Run-time code "generation"

JavaScript also allows to create constructor functions that create functions making possible a very expressive syntax for model objects and also run-time "compilation" of model access paths into functions.

Faceted objects

Component class is based on an abstract FacetedObject class that can be applied to any domain where objects can be represented via collection of facets (a facet is an object of a certain class, it holds its own configuration, data and methods).

In a way, facets pattern is an inversion of adapter pattern - while the latter allows finding a class/methods that has specific functionality, faceted object is simply constructed to have these functionalities. In this way it is possible to create a virtually unlimited number of component classes with a very limited number of building blocks without having tall hierarchy of classes - most components inherit directly from Component class.

At the same time milo supports inheritance mechanism when subclass can add facets to those that are already in superclass and to redefine configuration of inherited facets.


We also use mixin pattern, but Mixin in milo is implemented as a separate object that is stored on the property of the host object and can create proxy methods on the host object if required. Classes Messenger, MessageSource and DataSource are subclasses of Mixin abstract class.

Registries: dependency inversion

Components and Facets register themselves in registries that allows to avoid requiring them from one module. It prevents circular dependencies between modules.


The dependencies of Milo are Proto, an object manipulation library and doT, a templating engine (both are included in milo bundle).

No jQuery, Zepto, etc.

We do not use any DOM traversal library because:

  • DOM API is much faster (in some cases 30 times faster)
  • we do not want browser compatibility code to be part of the framework. If needed for some application, it can be implemented with polyfills. We may develop them for Milo if we need them, but feel free to contribute.
  • application start time is noticably faster

Instead, Milo Components can have Dom facet that includes several convenience functions to manipulate DOM elements and there is milo.util.dom - a similar collection of functions that can be used without components.

No underscore, lo-dash, etc.

milo uses library Proto that has a grownig collection of utility functions for the manipulation of objects, prototypes, arrays, functions and strings. Please see its repository for documentations and reasons behind the decision not to use third-party libraries.

It is bundled together with milo and all its functions are available as properties of _ object, you don't need to load it separately.


Changes log

See releases


Browser/nodejs reactive programming and data driven DOM manipulation with modular components







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