[comex]

That's funny; I think that's the only part of what the document proposes I like. -- Well, okay, that's not really true; there are a lot of bits that just make sense, either because they hurt performance for little benefit (holes in arrays) or they're just dumb (arguments.caller). But I don't like gratuitously locking things down in a way that makes highly dynamically-typed code harder to write, where it doesn't seem to solve a real unavoidable performance problem: for example, the ban on constructors leaking 'this', and the oddly specific recursion limitations. In general, the document seems to express the sentiment that only statically typed code matters, which I think is short-sighted. I also dislike, among other performance-unrelated changes, the "let's fix C" syntax bits, such as banning fallthrough, which is just likely to annoy programmers familiar with C (who are used to writing code that relies on it on occasion).

However, making nonexistent property accesses silently return undefined is just an amazing way to ensure typos in property names never get caught. I don't think `foo.bar || baz` is much to sacrifice - Python, for example, has getattr(foo, 'bar', baz), which works fine, and has the benefit of returning foo.bar if it exists at all, not just if it's a truthy value.

[stormbrew]

My experience is that the python way results in long and obfuscating chains of access checks. It's a fine idea to not make it the default behaviour, but there should be a way to do a chained check a-la coffeescript's '?.' to ease deep accesses, especially since in js objects are commonly used for data structures.

[lmm]

I've found that even in Python, only statically typed code matters - at least, statically enough that I can be confident that it works. I don't think the ability to have an object also be a map is especially valuable; code where everything is one or the other is clearer. These changes won't affect the ability to monkeypatch methods on individual instances (that's the one "really dynamic" thing that I find actually useful), will they?

[dustin1114]

It's kind of funny. ES6 seems to be making JS more "Python", while "strong mode" makes it more like Java/C# (at least to me). I'm open to worthwhile changes; I'm just thinking about the tens of thousands of lines of JS I've written with various utilities and libraries, and how they will eventually fit into ES6...I'm not too sure about strong mode, though. I guess we'll see how it all pans out.