Why JavaScript

It is interesting to note that Javascript is becoming more and more an assembly language for the web. Javascript is used more and more as either the direct "VM" for new languages (e.g., coffeescript) , or an additional backend. See here a detailed list

The newes addition is ClojureScript, a dialect of clojure that compiles to Javascript. Here is the rationale behind it. Rich Hickey, creator of clojure is behind it.

I find two interesting issues here:

Enyo is the WebOS javascript framework, so its main target is mobile platforms (but it doesn't allow you to interact with native services, the FAQ recommends wrapping it in phonegap).

It has the same "feel" like sancha (extjs) in that html is generated from javascript.

One nice thing it has is that it can create a class out of a control configuration:

enyo.kind({
    name: "Hello",
    kind: enyo.Control,
    components: [
        {name: "hello", content: "Hello From Enyo", ontap: "helloTap"},
        {tag: "hr"}
    ],
    helloTap: function() {
        this.$.hello.addStyles("color: red");
    }
};
 
// now create and use the new classes
new Hello().write();
new Hello().write();

Haven't tried em.

But you may find this useful.

impress.js is another example of the powerfull use of javascript+html5+css3. It is a clone of prezi. This means, it is a presentation tool where the flow is not through slides, but through zomming (focusing) on different parts of a large canvas. The steps are defined in HTML and the javascript package handles the transition. This means, authoring the presentation can be done in whatever HTML editor and not limited to a small subset of tools, as in prezi

source code: https://github.com/bartaz/impress.js