Infrequently Noted

What about this case?

MyClass.prototype.foo = YourClass.prototype.foo;

Should calling new MyClass().foo keep the weak ref to YourClass.prototype?

Yes, you'd get this behavior:

printMessage(); //”Whatup, yo?” o.printMessage(); //”Hello world!”

you implicitly get the "self.printMessage" since there's no weak ThisBinding for the call context so "this" points at window (or whatever your global is called).

I think this is one of the more lucid proposals for addressing the mysterious "this" problem in JavaScript. I'd even go so far as to say I like it. In most of the code I've written, these changes would have no side effect. I am curious, though, how this change would affect functions that begin in a non-pathological state, such as:

var msg = "Whatup, yo?";

function printMessage(){ console.log(this.msg); }

var o = { msg: "Hello world!" };

printMessage(); //"Whatup, yo?" or "Hello world!"?

o.printMessage = printMessage();

o.printMessage(); //"Hello world!"?

Should printMessage() be treated the same as self.printMessage()?

Since you'll be getting foo back via the MyClass instance, it gets a new weak binding thanks to the dot operator innocuously planted in there, meaning the ThisBinding is the MyClass instance.

Things still do what you expect.