ECMAScript 2015 classes and modules

We've seen so far that it is perfectly possible to build classes and even modules in pre ECMAScript -2015 JavaScript. The syntax is, obviously, a bit more involved than in a language such as C# or Java. Fortunately ECMAScript-2015, brings support for some syntactic sugar for making classes:

class Castle extends Westeros.Structures.BaseStructure {
  constructor(name, allegience) {
    super(name);
    ...
  }
  Build() {
    ...
    super.Build();
  }
}

ECMAScript-2015 also brings a well thought out module system for JavaScript. There's also syntactic sugar for creating modules which looks like this:

module 'Westeros' {
  export function Rule(rulerName, house) {
    ...
    return "Long live " + rulerName + " of house " + house;
  }
}

As modules can contain functions they can, of course, contain classes. ECMAScript-2015 also defines a module import syntax and support for retrieving modules from remote locations. Importing a module looks like this:

import westeros from 'Westeros';
module JSON from 'http://json.org/modules/json2.js';
westeros.Rule("Rob Stark", "Stark");

Some of this syntactic sugar is available in any environment which has full ECMAScript-2015 support. At the time of writing, all major browser vendors have very good support for the class portion of ECMAScript-2015 so there is almost no reason not to use it if you don't have to support ancient browsers.