Maybe he means that JS is a language where core language development is greatly outpaced by library development? The transition to ES6 is still underway (and ha

Maybe he means that JS is a language where core language development is greatly outpaced by library development? The transition to ES6 is still underway (and has been for awhile), but javascript has had tons of more "advanced" language features added both on the 3rd-party library side (jquery, underscore, lodash) and the transpiling side (coffeescript, typescript) for ages now.