js2-mode supports ES6 fairly accurately. But of course, that&#x27;s not enough, people keep asking for new things: JavaScript mixed with HTML, Facebook Flow support, JSX, new ES7 (still unstable) syntax extensions, and so on.<p>It would be easier with a more stable language. I.e. not JavaScript, which is still going through growing pains.<p>Even so, &quot;25 Open, 204 Closed&quot; seems pretty good to me.