Uncle is a tiny (1.3k minzipped) virtual DOM library. Ya know React, right?

What's different:

• Should be easy to understand because of it's small code base
• HTML templates - no JSX
• Templates can be precompiled for production (easy, TBD)

Live Demo on JSFiddle

var TodoApp = {
  items: [
    {text: 'Buy milk', complete: false},
    {text: 'Rob a bank', complete: true}
  ],
  toggle: function(index) {
    this.items[index].complete = !this.items[index].complete;
    this.update();
  },
  // render each item in context of TodoApp
  render: uncle.render('<ul class="todo">{{ this.items.map(TodoItem, this)  }}</ul>'), 
  // mount our UL as a child of BODY
  update: uncle.update(document.body) 
};

var TodoItem = uncle.render('<li class="todo-{{complete? 'complete' : 'active'}}" onclick="this.toggle($index)">{{text}}<li>');

TodoApp.update();

Use double curly braces (mustaches) to embed Javascript one-liners.

<li class="todo-{{complete? 'complete' : 'active'}}">
  Item #{{$index}}: {{text}}
<li>

Special attributes (or "directives"):

• key="unique{{id}}" - enables efficient reuse of DOM elements (as seen in React and other libraries)
• onclick="this.method(event, arg1)" - DOM 1 event listeners where this is your render context (not a DOM element)
• html="raw {{html}}" - same as innerHTML

Converts your template to a Javascript function, which renders virtual DOM.

var HelloMessage = {
  name: "Mr. Spock",
  render: uncle.render("<div>Hello {{ this.name }}</div>")
};
// HelloMessage.render() == {tag: "div", attrs:{}, children:[ "Hello ", HelloMessage.name ]}

Resulting function accepts two optional arguments: render(some_value, index). This can be used with native Array methods like Array#map(). In template's context both arguments are avaliable as $value and $index accordingly. If some_value is an object, it's properties are made avaliable as regular variables for convenience.

Allows any "renderable" component to update the real DOM. When you call HelloMessage.update(), it runs this.render(), computes a diff between two virtual DOMs and patches the real one if needed.

HelloMessage.update = uncle.update(document.body);
HelloMessage.update(); 
// OR
var updateBody = uncle.update(document.body).bind(HelloMessage);
updateBody();

One can call update() on-demand or put it in a RAF loop like this:

function updateDOM() {
   HelloMessage.update();
   window.requestAnimationFrame(updateDOM);
}
updateDOM();