[callahad]

Transformation of most ES6 features into functionally identical, backwards-compatible ES5 is trivial, and automated tools exist to do that, so you absolutely can use them today.

For example, default arguments are purely syntactic sugar for `if (arg === undefined) { arg = x; }` in the first line of a function. Still, I'd much rather write ES6's declarative `function foo(arg=x) { }` syntax rather than imperatively implement it in ES5 each time I need it.

[jwalden]

Technically, default arguments don't <em>quite</em>, <em>purely</em>, desugar exactly into that -- there are some scoping complexities to them as well (possibly only for functions having strict mode code), the details of which I haven't fully internalized. Your observation is otherwise correct with a little bit of handwaving. :-)

[jay_kyburz]

Absolutely agree, I was just confused by "all major desktop browsers will have support of the big ticket ES6 features" but I didn't think IE10 or 11 were getting any of these features.

[zeckalpha]

> I need it.

Need is a strong word.

[callahad]

In this case, "need" refers to the "if (x === undefined) { x = y }" pattern. Which is absolutely a need when implementing functions with variable arity.

If I need that pattern, I'd rather write it declaratively than imperatively. :)

[zeckalpha]

Variable arity is exactly the thing to which I refer. It isn't needed.