It's a pity that optional types are still missing in ES6. As I wrote: A good example is Facebook's Hack language that improve PHP in a sensible way and adds op

It's a pity that optional types are still missing in ES6. As I wrote: A good example is Facebook's Hack language that improve PHP in a sensible way and adds optional typing - something that would be great for ES6/7. In comparision the Java/C# type is static at compile time. Newer C# version have like e.g. Visual Basic 6 a variant type that is a tradeoff (as wasteful as a "union struct" in C). The class syntax in ES6 is just syntactic sugar. JS IDEs like WebStorm/PHPStorm/IDEA already can parse "classes" with JS5 syntax . But what about the arrow syntax: var odds = evens.map(v => v + 1); Or the iterator syntax that ES6 got from TypeScript: interface Iterable { [Symbol.iterator](): Iterator }