So classes in ES6 are something I have very mixed feelings about, on one hand all that is being added is syntactic sugar for what is already being done, I'd like to repeat that ES6 classes add NOTHING that isn't already being done and all it really does is pave the cowpath that is being used in places like node

Currently:

    JSONParseStream.prototype = Object.create(Transform.prototype);
    function JSONParseStream(options) {

    Transform.call(this, options);
        ...
    }
   
    JSONParseStream.prototype = Object.create(Transform.prototype);

    Object.defineProperty(JSONParseStream.prototype, 'constructor', {
        value: JSONParseStream,
        enumerable: false,
        writable: true,
        configurable: true
    }

    JSONParseStream.prototype._transform = function(chunk, encoding, cb) {
        ...
    }

With ES6:

    class JSONParseStream extends Transform {
        constructor(options) {
            super(options);
            ...
        },
        _transform(chunk, encoding, cb) {
            ...
        }
    }

That being said, the fact that previously you could not simply use the word class meant that despite efforts of people unused to the language (let me tell you how many half assed class libraries i've seen in code written by people who mainly code in python or java but have some web code as well), unnecessary inheritance tends to be avoided. The lack of a class keyword tends to get javascript writers to avoid inheritance for things best served by mix-ins or object literals, or whatever. I predict that adding the class keyword, while saving me some time will also cause an uptick to unnecessarily convoluted inheritance patterns as new users find they can implement all of their design patterns verbatim without thinking if they really need the ajax method, the json parser, and the url builder to all be in objects that inherit from each other.