[prodigal_erik]

In Python

  b = foo.bar
  b()

correctly invokes the bar method of the foo object. In JavaScript, you have to write

  let b = foo.bar.bind(foo)

because foo.bar gives you a function (not a method) that doesn't remember which object it came from.

[groovy2shoes]

I'm aware of what you have to write in JS, and I'd argue that that's the behavior that's to be expected. I'm actually more surprised by Python's behavior here. Lua works the same way JS does, as does Common Lisp.