Converting Object to Array using ES6 features

Use (ES5) Array::map over the keys with an arrow function (for short syntax only, not functionality):

let arr = Object.keys(obj).map((k) => obj[k])

True ES6 style would be to write a generator, and convert that iterable into an array:

function* values(obj) {
    for (let prop of Object.keys(obj)) // own properties, you might use
                                       // for (let prop in obj)
        yield obj[prop];
}
let arr = Array.from(values(obj));

Regrettably, no object iterator has made it into the ES6 natives.