> Var is broken in js because it does not obey sensible semantics

Scoping is broken in pretty much all modern dynamic languages.

Take Ruby for example:

    i = 10
    [1, 2, 3].map{|i| i * 3}
    [1, 2, 3].map{|j| j * 3}
    puts i # prints 3
    puts j # raises undefined local variable

Or let's look at Python:

    def maybe_append(b=[], n = None):
        if not n is None: b.append(n)
        return b
    print maybe_append(n=20) # prints [20]
    print maybe_append(n=30) # prints [20, 30]

So there's only a single instance of [], so that the default argument "grows" over time.