The naming of the language is somewhat confusing.

JavaScript is a trademark owned by Sun, and only the implementations by Mozilla (eg. Firefox) is rightfully called JavaScript.

The official name of the language standard is ECMAScript. But informally the names ECMAScript and JavaScript are often used interchangeably.

The current official version of the standard is ECMAScript 3. All major browsers support ECMAScript 3, and this is eqivalent to what we call Classic JavaScript.

Now the browser vendors are working together to create the next versions of JavaScript, called ECMAScript 5 and ECMAScript 6 or ECMAScript Harmony. (The naming of these future versions of ECMAScript are not clear yet.)

Now many of the features in these future ECMAScript versions are already available in Mascara.