Question

var foo = 'bar';
console.log(window.foo); // bar

Seems like variables get assigned as properties to this, but inside anonymous functions, this refers to the parent scope, but doesn’t assign variables to the parent scope.

function() {
    var foo = 'bar';
}();

window.foo; // undefined

What object do variables get assigned to in non-global scopes?

Answer 1

To cite http://perfectionkills.com/understanding-delete/#execution_context:

Every execution context has a so-called Variable Object associated
with it. Similarly to execution context, Variable object is an
abstract entity, a mechanism to describe variable instantiation. Now,
the interesing part is that variables and functions declared in a
source text are actually added as properties of this Variable object.

When control enters execution context for Global code, a Global object
is used as a Variable object. This is precisely why variables or
functions declared globally become properties of a Global object

Yet, these Variable Objects are not accessible. The only non-internal one is the global object, window or this (in global context).

The relevant section in the specification is #10: Executable Code and Execution Contexts.